nostr:npub19h7xd9z6skalpk053rqenfaqf6edljm7dj4s77kyf7xw05xvpz6slayzzp basically the arrows show consumption paths

For example LGPL v2.1 and LGPL v3+ are not compatible, neither license can include code from the other nor can you upgrade one to the other.

However both of these can be rolled into a GPLv3 license and therefore you can merge them under that license.