[yjftsjthsd-h]

Probably not necessary if they stack the licenses, since Apache 2.0 and AGPL are apparently compatible. That is, they can just add the terms of the AGPL in addition to Apache 2.0.

(IANAL)

[Quekid5]

IANAL too, but my understanding is that you cannot just "relicense".

You can add your own license to any changes you make and add your own license headers, but absolutely cannot change any existing license headers, etc.