Lacuna reads: While in play or in your deck, hand, or KO'd pile, Lacuna has the team affiliations of each character you control.

Goblin Glider Reads: Goblin Glider costs 1 less to recruit for each Sinister Syndicate character you recruited this turn.

So, if it's turn 3 and I recruit Lacuna, (already controlling a SS characer), can I also recruit Goblin Glider on her, or is she not considered SS when recruited and Glider still costs 2?

Thanks!

As long as you control an SS character, Lacuna is SS in your hand and will count as recruiting an SS character. So Goblin Glider will only cost you 1.