Back looping

I get how to do this BUT I can’t figure out haw to do it on the second leg (I’m making shorties) When I cast off and cut the yarn on leg 1, there is no live thread to back loop with for the second leg. I have been told to

rejoin at the crotch again to work the second leg, so you will have a working yarn when you get there because you’ve joined it in so you can work the leg

but I have no idea what this is suppose to mean. How do you rejoin at the crotch? The pattern calls for completing both legs before stitching the crotch.

TIA

I think rejoin means pick up the yarn you cut off and start working with it. You can leave about a 6" tail that you weave into your work after you’re done.

sue

See the thing is is that there isn’t any yarn that was cut off at the crotch. The yarn gets cut off at the bottom of leg 1.

Right, that yarn. Or just any yarn end you happen to have lying loose…

sue