I have a americauna x silkie hen that just started laying:.. Only lasted about 10 days then went broody. After a couple weeks I thought I would stick a couple eggs from a friend under her. Sure enough, 21 days later we got two Banty babies! They are doing well. We thought of separating as our 5 sex links are in the same coop... But decided to mess with them as little as possible. She is still stealing other hen's eggs and sitting on them. Should I get more fertiIle eggs? How long will she stay broody for?
I have to second PD Riverman's question.... does she still have her two chicks?
If so, then most likely she is just being slow to transition from 'hatching mode' to 'mama mode'. Some first time broody hens just get a bit confused. It is normal for a hen to spend a couple of days after hatch still on the nest because the little ones need cuddling and warmth more than food those first 2 or 3 days. The little ones do hop out from under her for short periods, but it isn't until day 2 or 3 that you see them out of the nest area for any length of time usually. (I say 'usually because I do have a couple of experienced broodies who seem to get the gang out within 24 hrs of the last hatcher being dry, but they are my 'drill sergeant' broodies! LOL)
Attempt to stop her from taking the other hen's eggs or check her multiple times a day to remove any she does get, if need be you may separate her for a couple of days to an area/pen/cage that makes her concentrate just on the 2 chicks she already has. When you notice her spending more time up and about with the youngsters teaching them to scratch and do general 'chicken things' and only going back to a nest area for a warm up once in a while or for the overnight then she is finished with the hatch mode and is probably going to be fine adding her back into the regular coop area. This would normally only take 2 or 3 days. She may snap out of it if you just move her to a different nest within the coop, but you would most likely need to block off access to her old nest area, and maybe even visually block it off.
Do not get additional eggs! The hen needs to concentrate on the chicks she already has and having already spent 5 weeks being broody so you should not encourage her to set any longer, even if she will.