TYPO3 BE permissions with two groups on same tree/page

Question

I'm looking for a way to simply manage permissions in TYPO3 with two groups on the same tree/page.

I have this simple tree page :

- Root
    - Page1
        - Subpage1
    - Page2
        - Subpage2

Group1 must have access to all pages from Root with edit access

Group2 must have access to Subpage1 and Subpage2 with reading access

I can only assign one group at a time to a page for permissions, how can I achieve this.

Thanks

Answer 1

Define the pages' group to "Group1" with write-permissions on all pages and allow read access for others.

Mount only the Subpage1 and Subpage2 for the Group2 (db-mounts)

Answer 2

Using be_acl extension you can set many permissions for many users/groups for each page.