I totally have to disagree, I would offer to SELL them some eggs (they have enough to buy a heated, solar coop after all, they can afford to buy them, right?) Just sayin'.
By the way, just to throw this out there, chickens have lived on this big old earth without factory produced rations, supplemented oyster shell, etc. etc. for EONS. I feed my chickens layer crumbles, and they BEG me to get out the their run so that they can free-range. I haven't had a soft egg yet, so they must know what they are doing far better than I do. They seem to have no problems filling their nutritional needs. If they should start having issues, then I will do whatever it is I need to do. With that being said, we have domesticated them, so it is our responsibility to take care of them. It sounds to me like you are doing a mighty fine job of doing just that.
I have an idea, go to the store, buy a couple dozen store-bought eggs, take them over to the high-falutin' coop and hide them in random places, one or two at a time. That would be a HOOT!!!