mmmm, do you have any chickens? If so perhaps one of them will take over the mothering, especially if you have a clucky chicken....perhaps for some reason your guinea has given up on the eggs that she has left, perhaps they are not viable? Can you candle them, or put them under a broody chicken, if you have chickens.
I had a guinea that was killed the night her eggs were ready to start hatching, I am fortunate to have a chicken that loves eggs and being a mum and she took the eggs and hatched them and became their foster mum, well they are now grown and have started to lay and she still mothers them! still try's to sit on them and they are bigger than her lol...You need to give them starter feed that is higher in protein, like game bird starter 26-28%...they need to have a high protein whilst young..., after 8 weeks grated cheese and finely cut up lettuce is a food they love! At least mine do...Mine are all eating mixed grain now and layer pallets, just the same as my ducks and chickens...... Some guineas are great mums and some are just terrible, so it will really be dependant on your Guinea, otherwise you can bring them up in a warm broody box, I am sure others will have great advice about this method, or you could google it on the net?
Good Luck and sorry that I am not that much help, but I wanted to pass on what knowledge I know and welcome to BYC hopefully others with more knowledge will direct you
Good luck and keep us updated
