Kinda long post….I thought I needed some background info 
So my grandma hatched a few eggs for me and threw in an extra chick when she brought them to me. The yellow one.
She says she got the mom at a co-op locally and they called it a “champagne” chicken. Now, my grandma isn’t the best at proper pronunciation, so they could have called it champagne or some other random name starting with a “C”.
I’ve asked for a picture of her hen and will update once she gets it to me tomorrow. My guess is that it is some sort of red sex-link but I have no idea what the adult looks like. She describes it looking like a “lighter colored production red”.
So this yellow one is a cross between a cuckoo marans roo and ______?
Any pre-hen guesses?

So my grandma hatched a few eggs for me and threw in an extra chick when she brought them to me. The yellow one.
She says she got the mom at a co-op locally and they called it a “champagne” chicken. Now, my grandma isn’t the best at proper pronunciation, so they could have called it champagne or some other random name starting with a “C”.
I’ve asked for a picture of her hen and will update once she gets it to me tomorrow. My guess is that it is some sort of red sex-link but I have no idea what the adult looks like. She describes it looking like a “lighter colored production red”.
So this yellow one is a cross between a cuckoo marans roo and ______?
Any pre-hen guesses?