Harley makes a splitter (they call it an Electrical Accessory Adapter p/n 70264-94A) for four-way Deutsch connectors. Perhaps they make one for the three-way Molex connector where you Coolfan is connected.
Alternatively I guess you could tap into the wires on the 325B Accessory Connector on the bike using Posi-Tap connectors.
https://www.posi-products.com/
ADDED: H-D makes an Electrical Connection Harness Extension 69201599A which can be used in conjunction with a Switched Circuit Adapter Harness 70264-94A. I found this infomation in the installation instructions for the Coolflow fan 26800128. It is a Note in section 4 of the Installation. It states "Install optional Switched Circuit Adapter Harness if more than one accessory must be connected between the P&A connector and fan relay harness connector." It is difficult from the diagrams and the fact that the instructions refer to the same item under different nomenclatures sometimes exactly how this would work but it might be worth investigating.
In any case please let us know how you proceed.