How to add new layouts to the subnavigation.

# Support

## Description
Hello all!! Maybe someone can help me: I have made a little extension to the bootstrap package to add a couple of layouts and maybe, if I manage, a couple of new content elements. So far I can make the layouts appear in the back end and the front end. Some only on the back... (it beats me why they don't work even when I make them identical) but my question is how do you make this layouts appear in the subnavigation (the one one the side column) I am slowly getting better but I find it really hard. Typo3 is very dense sometimes. Anyway, I hope everyone is staying healthy and cheerful. Thank you!!
[Is your question related to a problem? Please describe.]

Basically if the page doesn't use a Bootstrap Package layout, it doesn't get included. I guess is because my extension goes after the BS Package. So, how does one go about connecting them?
ANy help greatly appreciated