It seems to me that Lois made a great job being a big sister to Brian. I don't think he will be a problem to Lois and Clark's relationship.
But you must stop letting him sense Clark's feelings - it may become an intrusion to his privacy when his relationship with Lois deepens.
Clark must be feel comfortable with Lois knowing his secret, otherwise he wouldn't let his glasses out.
Eagerly waiting for more.
