I have a question I just ran into in a private campaign I am in with some friends. So here goes....

During a trip to another land (riding with The Queen,The Princess, and the Queen's champion) we discover that our driver (the lady driving our transport) is none other than the Evil Queen's daugter (whom we have never seen before so we did not know), now the evil queen had her daughter place a "hold person" spell on the seats of the transport we are in. The spell did not activate until all four of us were seated. supposedly ,according to the evil princess (the driver) all of us had to roll a wisdom save (none of us passed). So therefore we are all held in our seats and can not get free, we are as the spell states, parralyzed until released or the spell ends. But, since this is a homebrew campaign, the evil princess had used some sort of magical powder to change the dynamics of the "hold" spell. Thus, the spell does not end until released. Also, there is one empty seat that is a control seat. If someone sits in that seat we are all released but that person becomes stuck in their seat. In short, there will always be at least one person who will have to be stuck in order for the rest to be released. It gets quite complicated but we all understand the mechanics, however, there is the question of whether a "hold person" spell could be triggered this way, and can it be modified by some other magic to do as it was stated. We've asked the DM, but she told us she would have to look into it and has thus stated that the situation remains until otherwise stated. BTW, the only way for everyone to be released is by having both the evil queen and princess present to cancel the spell. It's a cute trap, but darn complicated and I've read up on the spell and really don't see any way this could work. Any one have any idea I could relay back to the DM? Oh and although this is a private campaign ,we do intend to take it public on discord in the future and we want to shake out all the bugs before hand, and this is one of those pesky "bugs" that we ran into, we have the campaign on hold until we can get this bug worked out, bassically can it happen or not? Or is there a better way to do it?

Looks to me that your DM didn't really cast hold person. She cast plot device. There's no way to cast hold person in that way RAW, but DMs don't need a clearly defined mechanical path to do something. They can just do it.

So thereticaly it could be done, but not with the "hold person" spell.Also, it wasn't the DM who cast the spell, it was one of the players, she's a 5th level wizard, evil alignment. Also the princess (her daughter) who was the driver who trapped us. She too is a 3rd level wizard. We were "rescued "(but not released from the trap) by one of our allies (Fey) who brought us to the fey land (where we were headed in the first place) to try and release us from the trap using some fey magic, to no avail. the best they could do is release the four of us, but in return one of the fey had to become stuck, it seems that at least one humanoid must be stuck for the others to be released. It's very complex. The fey are NPCs. So, the best way for this work would be to use some sort of magical trap, maybe with some sort of invisible powder or liquid spread on the seats that is magical. I sugested that to the DM but have not heard back as of yet. but as it stands, the hold person spell could not work in this way? am I correct? If so, I will pass that along to the DM and let her make the final decision. As it stands right now, the four of us are released, but one of the fey are stuck in the trap and cannot get free without canceling the spell which none of us can do. any ideas how everyone could possibly get free without at least one of us being stuck. We've been racking our brains to figure that one out, the Evil Queen tells us there is a way to cancel out the spell but she ain't tellin'.

With hold person alone, what you're describing can't be done. You said there was some kind of magic item, though. It's definitely homebrew, so I couldn't tell you if or how it works, but nothing in the rules necessarily makes the existence of a magic item that changes how hold person works impossible.

 That helps, So possibly the magical powder she used could change the spell in a way that makes it more or less a "programmable" spell to do as she wants it to do. Which is what it sounds like. I'm aware that homebrew opens up a whole new way of making things work in ways they were never intended to work. Guess that's the one thing that makes 5e so versitile. The only reason I asked in the first place is because a couple of the players who weren't used to homebrew and had some concerns and the DM still wants to stick with the situation as it is, so I guess we have to accept it. Anyone happen to have any idea how we could maybe cancel out the spell some how? It's a pain in the you know what having to have at least one usefull person stuck while the rest of us are free. 

If you can find a way to cast freedom of movement, that would definitely solve your problems. Other than that, I don't know. Have you tried putting a squirrel or a pig or something on the seat to see if it accepts it? Maybe forcing the person on the seat to move via shoving or spells would work?

Actually we tried putting something other than a humanoid on the seat, but unfortunately, the spell only accepts humanoids and not animals. We haven't tried casting a freedom of movement spell (not sure anyone even has that spell or not, I know I don't). As far as just moving or shoving, don't work, first thing we thought of actually, we are held too tight to hardly even move, almost as if we are paralyzed, but not fully, we can move some, but not enough to do any good. I'll check with the others in my "group" to see if any of them has something like a freedom of movement spell.

You could try Dispel Magic?

Now that's a thought. Might just work, I think at least one of us has that spell. I know our Queen don't, she's only a mystic and don't cast actual spells, her powers are all mental.  Nothing she can do will help any.