How to check if member exists in Account dimension

Hello experts, I have a requeriment to do.

In my account dimension I have two hierarchies. First one has nevershare members like this:

600001 / 600002 / 600003 / 700001 ...

In my second hierarchy I have two categories account.

a) Shared members of first hierarchy. Example: 600001 (Shared)

b) Accounts with different suffix (nevershare). Example: 600002_A1 / 600002_A2 / 600002_A3...

I would like to check if accounts of first hierarchy exists with category b in second hierarchy. The key is if exists account of first hierarchy with underscore, because all accounts have same "estructure" but one account can be one suffix or can be ten...

For example:

Account 600001 doesn't exists in second hierarchy because there isn't this account with underscore (_)