You have to reject Layla(and i think Erynn too, since you can't go to the beach with both of them, but i still haven't tried this combo).Thanks, i like Val, but she appears so late in the game that usually im already in another path, i assume that to get those scenes with her i have to reject all the other girls.
She can be combined with other LIs, no clue for how long... but up to this point she can be in a multi save(most of them can).