LOREnander, you SHOULD be able to stock locate those and have them shipped to your local store for free. First thing to try is to confirm Topanga still has your size, go to your champs, and give them the info to that store and see if they will manually confirm that (by telephoning them) and set up the transfer.
If for some reason they won't do that (or Topanga no longer has your size) then you need the SKU to locate. Best way to do this is to call topanga and specifically ask them for the SKU. Other way you can do it is go on ebay and just browse that shoe and hope you find a picture with the box that still has the SKU sticker still on there. Once you get that, have them run the SKUs for your sizes.
I will say, in my experiences the whole Champs, FA, FL SKU search is kind of hit or miss, and from what I remember the system has a stone age feel to it because they only search regions at a time not the whole country (like Nike would). You should emphasize you want them to search every region if possible. Def don't try to do this during peak business hours though. It's a tedious process for their staff (if you don't know which store they're physically at), and they can only search one size at a time.