I want to add a feature for this subclass where the player gets two extra spells that don't count against their spells known, and give them options from the Cleric, Paladin, and Wizard Spell list. But here's the kicker. I want to make it to where the spells they get are dependent on which spell list they choose from. Like for example, if they want to take a spell from the Cleric list, the second spell must be from the same list. How do I effectively put that in? If I wanted to do that, and the ability scales when they unlock more spell slots (2nd, 3rd, etc.) how would I do that?

You would have to use Options. Please see the Homebrewed Subclasses & Species FAQ #s 1 & 15: (https://www.dndbeyond.com/forums/dungeons-dragons-discussion/homebrew-house-rules/131411-a-homebrewers-how-to-faq). Make one feature where they chose from among the 3 spell list Options, and then another feature where the Options are “granted” and have the Options from the first feature are the prerequisites. Then attach the spells to the Options. If you need more information, don’t hesitate to ask.

So if I'm reading this right, then I would make one feature where they choose 2 spells, and add all 3 spell lists. That I understand. But I don't quite understand this line: "...and then another feature where the Options are “granted” and have the Options from the first feature are the prerequisites." Is the other feature that's only there to restrict the other feature? How does that work?

Not quite.

You would make one feature with 3 (NOT “Granted”) Options, 1 Option that grants the choice of the 1st Cleric spell, 1 Option that grants the choice of the 1st Paladin spell, and one Option that grants the 1st Wizard spell.

Then you would make another feature with 3 “Granted” Options that each use one of the Options from the 1st feature as a Prerequisite. Each of these Options would grant a choice of spells, but only from the correct spell list (Cleric, Paladin, or Wiz). If you are adding more additional spells at higher levels you could either add them to this feature as additional Options, or add them as Options to more features at higher levels. Just make sure they are all “granted,” and that they use the options from that👆first feature as their prerequisites.

Wow, that's... not all that simple. So create one feature that is not granted that has 3 options (those 3 spell lists), then create another feature that grants those 3 options. Is that right?

Not quite.

Create a Granted feature that has 3 not-granted Options (the feature must be granted, the Options must not be), and those Options must each grant a spell from one of the three lists. Then create another Granted feature that has Granted Options that grant the subsequent spells based on the first choice.

Okay, so I created the 3 class options. When I create the next feature, do I use the last one as a prerequisite? What then?

Yes, you use the Options from the first feature as prerequisites for the Options from the second feature, and attach all the subsequent spells to those Options. That way, if the first spell they choose is a Wizard spell it’ll automatically lock all the other spells they choose into being Wizard spells. Look at the Subclasses & Species FAQ #15 for info on how to set up a choice of spells determined by class: (https://www.dndbeyond.com/forums/dungeons-dragons-discussion/homebrew-house-rules/131411-a-homebrewers-how-to-faq).

Wow. After all this help, I still don't know how to do this. Thank you for your help. But I still have no idea what I'm doing. Unless you don't mind babysitting an idiot like me step by step somehow, I'm going to need to find someone to show me everything visually. Again, thank you for all the help.

Yeah, that’s why I referred you to that FAQ a couple of times, I wrote out complete answers with pictures there.

Maybe if you could explain to me where the breakdown in understanding is happening I could help you better.

Ok. So it's like this.

There's a subclass I want to make for the sorcerer. And one of the features I wanted to add is at first level they get two extra spells, similar to clockwork and aberrant mind soul. The only difference is they get to pick their spells, and the type of spells they get depends on which spell list they pick from: Cleric, Paladin, or Wizard. So like, a drop-down menu that asks for which spell list they want to pick from, and then after that, they see all the spells from said list there. And I want that process to repeat when they get their second-level spell slots all the way up to 6th level. So like if they choose the cleric list for their first-level spells, they can either choose the cleric spell list again or the other two spell lists when they get their 2nd, 3rd, 4th, 5th, & 6th level spell slots.

I also want it to be where the spells don't count against their number of spells known, consume spell slots, and use their charisma modifier. 

Okay, so, you can do most of that, but you will have to:

• Split that first level feature into two features.
• Make compromises.
• Program a shedload of Options.

1. Make a 1st level feature (we’ll call it “Feature A”) that has 3 Options, one labeled “Cleric Spells,” one named “Paladin Spells,” and one named “Wizard Spells.” (You can use the walkthrough in the Subclasses & Species FAQ #1 that I linked earlier for instructions on how to do that, including pictures.) Set it up so they get 1 Option at 1st level.
2. Then, open the Cleric Spells Option in the homebrewer and expand the Spells section and “Add a Spell” which will open up the Spells subform. Attach a choice of any 1st-level Cleric spell to that subform. (Follow the instructions in the Subclasses & Species FAQ #15 for a walkthrough with pictures.)
3. Then add a second spell choice the exact same way.
4. Then repeat that process for the Paladin Spells Option and again for the Wizard Spells Option.
5. Then create a second feature (we’ll call it Feature B).
6. Add a series of 5 “Granted” Options that all require the Cleric Spells Option as the prerequisite to Feature B. (Again, follow the walkthrough I mentioned earlier.) Set it up to allow them to choose 1 Option at 3rd, 5th, 7th, 9th, and 11th levels. Add the additional Cleric spells that they would receive at higher levels, one for 2nd-level attached to the 2nd-level Cleric Spell Option that they would get at 3rd level, one for the 3rd-level Cleric Spell Option that they would get at 5th level, etc. (Again, use the walkthroughs.)
7. Then repeat that process to add the 5 Paladin Spell Options to Feature B.
8. Then repeat that process to add the 5 Wizard Spell Options to Feature B.

What will happen is they will choose their spell list and get their two spells, just like you want. Then, at the higher levels they will automatically receive the Options that correspond to that first choice, and will be able to choose those higher level spells then.

The compromise is they won’t be able to choose different spell lists at higher level, their choice will be locked in when they make it at 1st level. That’s the best you can do.

Okay. I see. And If add all allow them to choose any spell, as long as it's from the three spell lists spell list instead, all of that will work the same?

I’m not sure I understood your last post.

Basically, if I instead make it to where they can choose two spells from all three lists, everything you posted was still apply?

Sorry for the delay. If you are making it so that they could choose from any of the three lists then you wouldn’t need the second feature, and you wouldn’t need the prerequisites. Heck, you wouldn’t even need the Options at all. You could do everything with multiple applications of the Spells subform.

Ok. So I essentially made everything easier on myself.

Yes. It’s just a different compromise is all.

Ok. Thank you for your patience and all your help.