I think we are all trolling too much here and posting way more answers than question ask.
So let me remind
original question wrote:
My house is wired to have an outside generator plugged into support electrical power failure. I was wondering if I could plug my motorhome into this outlet and use my motorhome generator ?
It seems that it would needs some rewiring or added wiring or maybe not.
The way I read it the OP has a cord attached to his house transfer switch that can be used for emergency power supply.
We don't know what plug the cord has, while RV usually don't have sockets bigger than 20 amp.
Meaning with some adapters the house can be plug into RV 20 amp power system, but it would take electrician to make bigger plug to take advantage of full generator power.
I always wonder about conversions coming with 22kW generators on board and that might be the answer.