Hey, guys. 

So, I'm new to d&d beyond forums and want to give a shout-out to all this great community. 

Guys, I'm gonna be organizing an Eberron campaign and I have this question i haven't found an answer for in your forums -even though the subject has been treated, i still haven't clarified this subject. 

In my group, I have no spellcasting classes as the fighter, the monk and the rogue with dragon marks. 

The problem is.... Do they have necessarily to multiclass as wizards for instance to be able to use the spells granted by the mark? They can't have access to theses dragon mark spells being a fight, a monk and a rogue? 

At first I thought that the mark in itself granted this capacity to cast those exclusif spells, but then again... Without the spellcasting feature, they normally couldn't, right? 

So, dragonmars are convenient just for spellcasters? 

Thank you very much, guys. 

So two parts to this answer.

Some Marks have Spells they innately can cast (example mark of handling human can cast animal friendship and speak with animals through the primal connection ability)

as well as the Spells of the Mark feature.

The Spells of the Mark feature adds spells to the spell list of any spell casting class which makes them available to learn as any class with a spell-casting feature.

Ok, guys, thanks a lot for your answers. In that sense, and given the monk character has the Jorasco dragonmark; the fighter the sentinel dragonmark; and the rogue the shadow dragonmark.... To make them being able to cast those dragonmak spells without renouncing to their respectives martial classes, should I... 

Allow them to multiclass and have wizard class to learn them? ( Wouldn't like this one though... )

Or what solution would you suggest for them ( keeping their classes) to have the dragonmark spells of the mentioned houses? 

The Fighter and Rogue characters can easily get the Spellcasting feature, by picking their respective subclasses.  The Fighter should choose Eldritch Knight as their subclass, while the Rogue should choose Arcane Trickster.  No need for either to multiclass.  This could, however, disrupt the planned builds of those characters, so that will be on the player to make that decision.

The Monk, on the other hand, has no spellcasting subclass.  As such, they will have to multiclass.  Since the Monk is probably going to be focusing on Wisdom anyway, they could consider Cleric.  This may clash with the theme of the character, but that in part depends on what Divine Domain (subclass) they choose.  War Domain, for example, has options that make the Cleric much more martial.  Druid is another option, since it also uses Wisdom as the casting stat, but Wild Shape doesn't really work with the Monk features, at least as far as I'm aware.  Don't get me wrong, a Dire Wolf karate chopping people to death sounds hilarious, but I'm fairly certain the rules don't allow you to use Flurry of Blows, for example, while Wild Shaped.

If it were my game, we would just not use the feature. Especially since no one is benefitting from it. If some got the spells and some didn't, you'd have a minor balance/"fairness" issue, but as it is, all of your characters are equal so there's no problem here.

If the problem is that you want the flavor of the spells, I'd just houserule them to be 1/use a day similar to other racially granted spells.

There is an item in Exploring Eberron (a homebrew book) called a Dragonmark Focus that, in exchange for charges, non-casters can cast their Spells of the Mark with a higher charge cost depending on the level of the spell they are casting. like, 1 charge per spell level. You could do that.