was looking for the exact same case. building my own tabbed content block.
the approach of @dsouzaj86 works pretty well. I tried it. thank you very much! Only thing i don’t get is the parent property to allow appearing the tab-content only in tab-group. at the moment i can place it everywhere.
tab-group:
<InnerBlocks allowedBlocks="<?php echo esc_attr( wp_json_encode( array( 'acf/tab-item' ) ) );?>" />
tab-item:
<InnerBlocks parent="<?php echo esc_attr( wp_json_encode( array( 'acf/tab-group' ) ) );?>" />
seems parent gets ignored.
