I thought we had someone on here that tried that and I believe his 'regen' function played all heck with the SA cylinders.
Yes< i had that trouble,Even the dealer said there was some sort of 'situation'' that would not allow me to use the curl hoses to run the SA cylinders. Of cource I didn't believe them, and proceeded to try, and failed.
I'm not sure if all tractors are set up with the 'regen' way but if it is then that option is out.
There is a company in Sedalia Missouri that makes grapplers and other implements for compact tractors.. One of the things they make is a sharing device for a 3rd control.. it is called xtra valve you can find it at this web address if your interested.
Products - Precision Manufacturing
Regards
Bob