Then yer set...
Tell yer buddy to move into the 21st century...lol
Like I said....
Remove the regulator from the Webber Q, really easy. Add a Male quick connect.
All these links are what I bought
SHINESTAR Propane Quick Connect/Disconnect Adapter Fitting for Weber Q 100, 1000, 200, 2000, 1200, 2200 Portable Gas Grill - 1/8 in Female Thread x 1/4 in Male Quick Connect Plug https://www.amazon.com/dp/B07NJB11FF...ing=UTF8&psc=1
Google how to remove the regulator, really easy.
Do the same on yer other stove...Google it too
The Y is this....
DOZYANT 1/4'' RV Propane Quick Connect Y Splitter Adapter for RV Trailer and Quick Connect Propane Hose Connect to Motorhome Tabletop Grill, 2 Way LP Gas Adapter 1/4" Quick Connect or Disconnect Kit https://www.amazon.com/dp/B07MNXDXNC...ing=UTF8&psc=1
I also got this 12' extension. RV came with a 4' for my outdoor kitchen but way short for a BBQ
DOZYANT 12 feet Low Pressure Propane Quick-Connect Hose, RV Quick Connect Propane Hose, Quick Disconnect Propane Hose Extension - 1/4” Safety Shutoff Valve & Male Full Flow Plug for RVs https://www.amazon.com/dp/B06XK43NL3...ing=UTF8&psc=1
Now I'm not 100% sure you could run both the Webber and Blackstone at the same time...but pretty sure u can. So something fun to test out
Holler if u have any more questions