Ah, I still managed to make the adjustment for the maxi-cosi with a little fiddling.
I had the problem that the presser foot could only handle buttonholes of max 28mm, but thanks to a few tips from friends I managed to make a larger one.
It’s actually not that difficult, you stitch 2 buttonholes on top of each other slightly offset so that you get the correct length. And then you open it.
Here are some photos of the adjustment and the result.

First mark the buttonholes neatly on the fabric. Thank you PEEPS for the pattern.
_CDL_MASK_31__Length and direction with dots.

Lines written in chalk.
_CDL_MASK_53__And sew with the buttonhole foot.

4 beautiful buttonholes opened.

Blanket in the maxi-cosi
_CDL_MASK_86__With “trial baby”

Wrapped up nice and warm 😉
Well that’s it for today, unfortunately there are other things that have to be done before the baby arrives that have nothing to do with sewing :-/ Too bad, but what has to be done, has to be done…