what are promises and wishes? I now have two families and what to play as both but the only way I see to do that is threw something I don't remember the name of and it says the premisses and wishes will be removed or deleted or some thing. I don't recall. it sounds bad, but I really want to play as sims at multiple different lots. How do I do that? will these things be restored when I swich back?
Also when I did switch active families the game crashed. It'll take me time to figure out why.

Also can you really not build a mermaid in CAS? and Photography isn't a personality trait? whats up with that? and what EP has the apple trees?

1. Wishes are the wants that the sims roll. They appear on the top of the UI panel near the left. Promises are the ones you agree to let them have by left-clicking on the wishes, and they appear just below them, four at a time. You can refuse them by right-clicking on them. They get happiness points when they achieve them.
When you rotate families, these normally get deleted. It's not terrible, though. It just means some happiness points that they can't get. It takes a little while for new wishes to populate when you get back to the family.
With Master Controller from Nraas you can set it so that those get retained when you switch families.

I don't know about mermaids since I don't have Island Paradise. I think that Uni or some such added a trait that encourages photography.

I'm pretty sure apple trees are base game, but normally you get your first apple tree by finding a seed in the world or buying an apple at the grocery store or picking an apple from a tree you encounter somewhere. But! you can plant apple trees and so on for your sims using the cheat box you get by typing Shift-Control-C. Then type "testingcheatsenabled true" into the cheat box, followed by "buydebug on." Now when you go to buy mode and "sort by function" you see a question mark in a box. Click that and a whole menu of spawners, plants, and other oddments unfolds. The garden plants cost nothing so I use them in landscaping both residential and community lots now.

There is a trait for sims that deals with photography. I just can't remember what it's called right now. Just search through the list and you should see it. ??Photographer's Eye?? Maybe?

Photography is a skill. Photographer's Eye is a trait that makes the skill easier to learn. (And yes, Apple trees are base game. )