chargeability problem, please help

My wife has an approved I-140(EB3) with PD 01/2004. I also have an approved I-140(EB2) with PD 01/2006. My question is

Can we combine together, that is, use my EB2 category and my wife's PD to file 485?

I know people can use the spouse's country in which he/she was born by cross chargeability. But I don't know if we can file 485 in this way?

So many thanks,

Hu