I’m attempting my first pair of mittens, and have started them over about 3 times now. Here’s my question:
How do you properly “add 1 stitch” in the crease of the thumb? (that is, right after you’ve put the thumb stitches on a holder…) I’ve tried, but it makes big holes in that area…
Hope that makes sense. PLEASE HELP!!! Thanks!!!
-Rheanna 
well i haven’t made mittens yet but i can say that when i have done the bar increase (lifting that little inbetween stitch) i have always had a hole when i lifted it and then just knit it like normal. HOWEVER if i knit into the back of that loop instead i don’t get that hole.
not sure if that helps but if not there are a lot around here waaaaay smarter about these things than me! 
What have you tried? I would probably use a M1 increase, and if it still left a hole after I’ve knit a few more rows and tugged it around a bit, I’d probably just close it up with another piece of yarn. But that’s just me. Maybe someone has a more ‘proper’ technique.
Thanks for the replies…
I’ve been trying the Make 1 stitch. But it has just dawned on me that I am knitting it through the front… am I supposed to from the back? Then it won’t make a hole?
Yes! When you make a M1 stitch, you need to knit into the back–the little loop that’s such a pain to get at. That’s what makes a tight stitch.