combo+combo+cab - how do I put this together please?

The back of your YCV50 has a send jack. Run that to the input of your Peavey Bandit.

This is from page 3 of the YVC50 manual:
The 1/4 inch TRS Send jack can be used as part of an effects loop in conjunction with the Rtn jack. It can also be used as a direct line out (preamp-out). The -10dBu output is ideal for most guitar effects pedals and professional signal processors. You can also use this output to slave the YCV50 with another guitar amplifier by plugging into the Rtn jack of the slave amplifier.

Hello

I play live gigs (usually bars) using a Traynor YCV 50W 1X12 tube amp and a 2X12 cabinet. As a backup I have a Peavey Bandit 112 solid-state, 1X12 100W amp. Is there a way that I could patch these three together to get the most out of my equipment?

Thanks!!

Are you trying to damage your hearing, or just create more difficulties for the sound guy?

Any venue I've played in the last 30 years that needed more volume than a 50 watt tube amp could deliver usually had it's own sound system with tech. You'll generally be better served by using smaller amps, and miking them up when necessary. If the problem is you can't hear yourself, take a look at where your speakers are pointing, then tilt them or raise them to point at your ears.

I was busy thinking what type of sends and returns your equipment might have when I read Moonrider's post and thought, oh yeah ...... 50 watt tube amp. That is loud isn't it? Do you just want more speakers? You might be able to use the 2 X 12 cab with your Traynor. That wouldn't necessarily be louder, but as stated above ... do you really want louder? Oh, and welcome to the forum. :D