Application for two grants at the same time

I wonder if anyone has ay experience of dealing with HMCTS in this situation as last time I dealt with this situation we had regional probate registries who provided advice and guidance!

A dies naming B exor and leaves everything to C
C dies shortly after also naming B exor and leaving everything to D & E

B would rather not act in either estate unless it will cause significant problems.

If B renounces D & E can take Grant of Letters of Admin with Will annexed over C’s estate which would then allow then to do similar for A’s estate.

Has anyone tried to get HMCTS to deal with this situation by making both applications at the same time noting in the application for the second that it cannot proceed until the first is completed?