I've dropped few words on menu naming mess earlier.
Remove "a" from Add tab group to a new collection.
A good example already exists there - Move group to new window.
BTW When you add 6 cakes to sister's 5 cakes, you are left with zero cakes. Your cakes belong to the target group now. So, Copy tab group to new collection instead of Add would be better.
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MS Edge Dev 95.0.1020.5-1
Debian Bullseye GNU/Linux 5.10.46-5, X.org 1.20.11, IceWM 2.1.2
Nvidia GeForce GTX 650, Driver 460.91.03, systemd 247 (247.3-6)