I ran into this problem before during the development of our title blocks. From the drawing that you supplied it looks like the WD_TB was inserted seperatly from the title block. The solution that we came up with was to insert it in the base title block, then insert the title block. The WD_TB should be invisible after that. The WD_TB should also be an attribute in the title block, not a block. Attached is a sample from our title block here.