A trademark is registered (for more than 12 years) in the name of four persons trading as a partnership firm (XYZ). With time, the firm undegone multiple changes and currently it has three partners out of which one is the original one. There is another partnership firm (ABC) being the related firm of XYZ is using the trademark from last 5 years as a business policy on tacit understanding or lack of licensing knowledge. Now, XYZ wants to license the registered trademark to ABC. Whether the license can be effective retrospectively, that is, from last five years since ABC is using the trademark. And, whether a partnership firm (not being a legal entity) can license the trademark to anopther partnership firm. Or, the current partners of XYZ have to license the trademark to current partners of ABC (with statement that the said partners of ABC can use the trademark only for the business of ABC and not independently)?
Thanks in advance.