What is the changelings opinion on same sex couples?
Would they discourage them because they would produce no offspring?
Or would they just accept them?
Or would they hypnotise them into believing they were straight?

As long as there was love to feed off of I don't see why they'd care. Their traditional priorities are going to be predatory, and after reformation they're all about individual choice.

...oh right, THIS group. I think they'd just find ways of breeding gay ponies without needing hypnotism. Shapeshifting is OP.

Well the whole point of this group is the gradual extinction of ponykind, so I don't see why lack of offspring would be a problem.