Rejoinng wool to a garter stitch band on a holder when there is no tail

Hi Fellow knitters’
I am at the stage of knitting the neckband on a baby cardigan . To do this I have to start with 6 stitches from a stitchholder which is a garter stitch band that was knitted with the front. How do I rejoin the wool to do this and leave the band looking neat.
All the videos I have found already have a tail of wool to use,
???
Cheers

Welcome to KH!
You can just start knitting with the new yarn and then snug up the end later when you weave it in. It won’t really look neat until you’ve worked several rows and woven in the end.