Be very careful when dosing the Nutri-Drench. As fine of a product as it is for supplementing essential nutrients for compromised birds, too much of a good thing can be a bad thing.
The vitamins, minerals and amino acids N-D contains, while essential, are not sufficient compensation for the same...
It depends on the breed. A LF Rock, JG or Cochin would eat a great deal at 7 weeks. A Serama or Silkie, not so much.
I'd feed her till she doesn't obsess about food.
Do you really plan on dealing with this the chicken's whole life?
I haven't dealt with crossbeaks but a picture may help others...