Merging Facebook Pages = Death for Google Ranking?!

Hi all,

together with my colleague, we are facing the following, a bit more complicated scenario. We'd be more than happy, if could help us out!

Briefly:
We have a brand with offices in different cities (1x per city).
Each one of us has his own Facebook- (and google my business-) page. However, we're sharing one common webpage and put our different office locations into subpages.

E.g.:

1. City of Berlin with proper Facebook und google my Business page, common webpage

2. City of Munich with proper Facebook und google my Business page, common webpage

3. more cities ...

We now want to merge both Facebook pages, however we fear that this will have negativ consequences on our google ranking, since we then won't be able to link our main Facebook page with the different local "Google my Business" pages.
Note: We got very good reviews on the google pages.

==> Is our fear justified?
==> How do we solve the problem in the best way?

Thank you in advance for your support!

Best wishes,
Hans : )

As a reference, these are a few of the pages I'm talking about:

facebook. com/mysoulofyoga (Munich), soulofyoga. de/muenchen/ and google. de/maps/place/Soul+of+Yoga