What
does she feed her dogs? Doesen't sound like any kind of raw diet I know of, ground egg shells, marrow bones (both no no's) and no chicken bones (big yes)
Cooked chicken bones (or any cooked bones) should not be fed.
Raw chicken bones however are soft, pliable, and are simply crunched up and swallowed. Marrow bones are far far more likely to cause problems as they are so dense.