In this situation I think it might be best for you to try to follow the 90/90/90 in 90 days theory .... that's 90 new foods/90 new hands/90 new toys in 90 days ...
Yeah, you don't have to follow it to the letter but it is a thought process that you want to expose these guys to as many new things as you can before they turn a year old or so, especially with what they have been through in their short lives.
Glad to see that they are "tails-up" in their food dishes, that's a great sign, now, hopefully, you can get them off those yuckie seeds and onto a really healthy diet.