WY0 is the built-in analog output located on the top right side of the built-in I/O of the BRX. So, are you saying when you add the analog output card to the BRX that WY0 stops working? Or are you mistaking WY0 as being the first channel of the added-on analog output module?
In Do-more Designer, if you pull up the Dashboard view (View --> Dashboard, if it's not up already), then if you hover your mouse over your analog output module as pictured, it will tell you the address of the channels. For example, if your BX-08DA-2B module is the only added on module, then if you hovered over it, it will show you that the first channel is WY2 (not WY0). It occupies WY2-WY9. The build-in AO is WY0-WY1.
<<NOTE: After posting this, @kc4ums pointed out to me that the BX-DM1-36ED1-D doesn't have any built-in analog. Oops on my part.>>