Register is related to Store. Store is related to Retailer. 
Aids is a form of Aid. Aids is a type of Virus. Virus is a different concept from Bacteria. you are likely to find Bacteria in/at/on Mouth. 
Register <--RelatedTo--> Store <--RelatedTo--> Retailer 
Aid <--FormOf-- Aids --IsA--> Virus <--DistinctFrom--> Bacteria --AtLocation--> Mouth 