Do you need to be certain to get all of the coding region (e.g. promotor through 5'UTR)? Or is there some flexibility in exactly which parts of the gene you need to amplify?

The fact that the genes are adjacent won't matter, not with several kb of sequence distance.

Do an alignment of the genes in the gene family to find regions that flank your gene of interest that are divergent. Use a primer design program & limit primer choice to those regions. You don't need much of a mismatch to get specificity.

Good luck!

Thank you for the response. I am targeting all of the coding region and also promoter and downstream regions. Katie A S Burnette