I need to know if it would be ok to manufacture add-on products for another companies products? We manufacture playset accessories and would like to make wooden add-ons for another manufacturers playsets. Some of the add-ons would be our own designs, some would be similar to the designs that the other company already offers but not exact. Would this be infringement? These parts would be made specifically for this manufacturers playsets and when we market the add-ons we would like to mention that they fit that manufactures playsets and which models. Similar to an aftermarket company making a replacement hood for a "Chevrolet Tahoe"