I would be worried about a few things.
1) when the engine is running it could either create suction on the line from the stove,
2) or push fuel
out of the stoves return line.
3) if the stove was running and not the engine it could force fuel
back into the engine thru the return line.
4) if both are operating at the same time could it over pressure the system.
I am far from a diesel mechanic
, and am also a pretty poor plumber, but I don't think I would try this without some expert guidance.