I have a table that contains a list of projects. Each project may be a parent, child, or grandchild project. One of the fields 'parentproject' identifies the relationships. If the field is populated with the ID of another project, then the referenced project is the current project's parent. I have a report with 2 groups to display these like this:

Group1................Parent
Group2.....................Child
Details..........................Grandchild

This report seems to work OK and is built on the following SELECT

select r1.system, r1.rtp_id, trim(r1.st_name) + " / " + trim(r1.termini) + " / " + trim(r1.project) as st_name_a, r1.lead, r1.del1, ;
	r2.rtp_id, trim(r2.st_name) + " / " + trim(r2.termini)  + " / " + trim(r2.project) as st_name_b, r2.lead, r2.del1 as del2, ;
	r3.rtp_id, trim(r3.st_name) + " / " + trim(r3.termini)  + " / " + trim(r3.project) as st_name_c, r3.lead, r3.del1 as del3 ;
	from rtp_projects r1 ;
	left join rtp_projects r2 on r1.rtp_id = r2.parentproject ;
	left join rtp_projects r3 on r2.rtp_id = r3.parentproject ;
	where (r1.parentproject = 0 or isnull(r1.parentproject)) and ! isnull(r1.st_name) and ! isblank(r1.st_name);
	order by r1.system, r1.st_name, r2.st_name, r3.st_name	

Now comes my problem, there is a second table that also contains a list of projects that may be a child to any of the projects in the first table. I would like to include these projects in the report as well, either as a child, grandchild, or great-grandchild. I'm not clear on how the select should be modified to do this, and the report also. Do I need 2 or more detail bands or additional groups, a select with a UNION or more JOINS, etc?

Any pointers will be appreciated. Thanks.