Good news! We caught the adult male last night. I dropped off both mama and him at the shelter for neutering/spaying this morning. I will pick them up after work.
I was hoping to catch a kitten or two, but no luck. The snow really hindered our progress--the traps kept sticking, and with people out shoveling/snowplows/etc. it was not quiet enough for them to come out.
I'll set the traps again tonight.
PS Both Benny and Ringo were very curious about the activity out on the porch. Benny nearly bolted out there, but we stopped him in time. Given that both cats were in cages under towels, he wouldn't have gotten to see them anyway.