Re: enable theme 1.2 sitewide
This is the stone-knives-and-bearskins approach, but you *could* do it by hand (or use some SQL) by going in to the database and doing it directly.
User blogs for WPMU are in sets of db tables as wp_#_tablename, where # is 1 (the main BP site), 2, 3, 4 and so on for each blog and tablename is the name of the table in question.
Tables called wp_#_options (again, where # is 2, 3, 4 and so on) have a row in the column option_name with the value current_theme, and with the value in the option_value column being the name of the theme used for that blog.
You could either go into each one by hand (very suboptimal with 200+ blogs to fix) and edit that field to be the name of your child theme you want use, or run an SQL update query (which I am underqualified to attempt to write for you) to do it quick-like.
Disclaimer: I may be wrong about this — it might be more complicated than that. But failing a better solution, it might be work a shot.
