Pegnant sunburst platy help. Can you help?

Hmm, I wouldn't put adult fish in a breeding trap, and ironically never a pregnant one! Moving a pregnant fish can stress it into aborting the little ones within. What you could do is make sure you have plenty of hiding places such as bushy plants (java moss takes the cake here) or decorations with holes too small for the adults. Then all you have to do is wait the three weeks and net out the fry. It'll helpt ensure the survival of the adult female. Also, if all fry are rescued, though this seems a bit mean, yu'll be overpopulated. Paternal predation is necessary to keep tank population in check, though it doesn't always work out that way.