Presumably, this is the premise behind T0 [1] in that it would allow beneficial owners, instead of brokers, to be able to lend their securities to short-sellers. In that case, there is no problem of tracking ownership - if you lend your shares to the short-seller, you're no longer the beneficial owner, and any agreement, like paying of dividend, has to be worked out between the two parties without involving a broker.

[1] https://motherboard.vice.com/en_us/article/overstock-wants-t...