Can you add some photos so I can see how you have everything hooked up?You need a selective control valve (SCV) for any attachment that doesn't have one built in but requires one. Beyond that you can run as many attachments as you have valves or diverters for.
You can have hoses made to use the same valve for multiple functions that are not needed simultaneously. For example, I'm able to feed a backhoe thumb or a hydraulic top link with the same valve. There's never a conflict with those two uses.
The backhoe and things like wood splitters have their own valves so they just need constant flow such as provided by the power beyond loop. You are just borrowing flow from the tractor and controlling the attachment with it's own valves.
I run my grapple off the loader diverter while the BH is attached and would function but is not in use. No hose swapping is necessary to stop and begin BH operation. I'm also planning to run my three point tilt off that same diverter. This may occasionally cause conflict but I don't expect it to be frequent as I don't do finish grading with the grapple still on or at least in use. Once the grapple work is done the tilt function can have the diverter ports.
North Georgia. I’ll have to look into it. They had the thing for 4 days. I just wanted the stuff and would have installed myself. They said for warranty they needed to do it.OK,
So to answer the original question, YES it can be hooked up so both the new 3rd function and the backhoe works at the same time. BUT, it would take some skill and thinking outside of the box that your dealer obviously does not have.
Diverter kits (Artillian, Summit) are much better suited on a 1-series than these kits, main due to available real estate. Do you think you have any recourse with them to take this back and refund it?
Where are you located?