i can switch seats on the horse, but i cant seem to have anyone else get on it with me or vise versa.

also there seems to be an issue with trying to get the minicopter seating to work as well. It might be interfering with another mod. It freezes me in place when i try to get on the mini and there are no extra seating

Because you can't use this and the minicopter seating plugin at the same time
https://umod.org/plugins/minicopter-seating