Heya, VegasChick!
Those chicks DO grow fast.... I was amazed in the size difference that was noticeable in the Marans that hatched a day apart. (The Faverolles had their act together and all hatched pretty much on the same day except for one straggler). I'm glad your sister is enjoying them. She is such a joyful person! Please do keep me posted on boys v. girls.... I hope you keep a Marans hen or two for yourself as they're really pretty coloring (and, supposedly, of good lineage).
BTW, the large off-white egg in the carton was FERTILE! Big ol' bullseye. Guess your roo was mega potent....that or there's some rendez-vous'ing and 'splaining to do in your neighborhood! How long ago did he exit the scene?