Item Variations in a Purchase Order - Square for Retail

[Craftinomicon]

I am trying to create a purchase order using Square for Retail and am running into a couple of problems. 

#1: I select the vendor I want to write the purchase order with. I would think that would narrow down the list of items I can select from to JUST those marked with that vendor - but that does not seem to be the case. Do I need to search for each item over and over again to create the purchase order? 

#2: When I do search for and select an item - it doesn't allow me to specify variations of the item. For example, if I want to order a shirt from a vendor - I will want to be able to say how many of each size I would like. I don't see a way to do that. 

Thanks in advance for your help.