We're just starting a campaign in the Ravnica setting and I'm curious as to how we're to interpret Guild spell acquisition for Dimir characters with the False Identity feature? Do they get all of the Guild spells for their secondary faction? None? Some? My thought was to try to strike a balance by allowing one choice from the secondary Guild spell list per level to illustrate the challenges of leading the second life, but open to feedback.
Dimir would only get House Dimir spell as they are not leading a true second life it is just a persona that they can just easily throw away if they desire.
Instead House Dimir characters would use illusion an trickery to make people think they were using magic from other houses.
Also the False Identity feature is limited to documentation and history basically having the necessary paperwork and the knowledge and skill to back it up and make it hold up under scrutiny not actually taking other guilds magic.
The only way I would allow it is if the person switched from another clan to Dimir at a later time and had already taken the spells from their previous clan.
A character from House Dimir should be using other methods to try to learn those spells if possible. For example, maybe a Wizard tries to acquire some scrolls to scribe into their spellbook, or somebody else takes a Magic Initiate feat. It won't cover every circumstance, but that's a large part of the fun: trying to figure out your way past the challenge!