It's always good to be straight up with your legion members. Ask them what they want to get out of a legion and go from there. Keep them in the loop of all talks with other legions, soon enough you will notice what you all want to get out of a legion which will help narrow your potential choices.
Focus on your goals in the game. Remember it is a game, so don't get too stressed out about merging with another legion and don't rush into it. Fly safe and relax it'll all work out