BuddyPress.org

current theme is latest u-design with childtheme for css search.php functions.
Any Help appreciated in this. Apparently this is the 4th time the org has attempted a go at buddypress and they end up just uninstalling the whole thing. I just took over as dev and am very familiar with wp but bp is a very different beast. Plus its info/docs are lacking unorganized and outdated.

The site seems to work with bp out the box, everything looks good. Except when comment or reply is pressed then NOTHING happens..well ok the page moves up and down a bit, but no comment form. Change to 2014 theme and works, change to our theme and nothing.

There are so many, I MEAN 100s, of pages about buddypress theme integration/conversion online and many of them are out of date.
One place I read create a folder in current theme called buddypress and add all files from buddypress/bp-templates/bp-legacy/buddypress in there and change as needed. Another said we can name the folder community instead of buddypress. One said will not work if not multisite…will not work if in directory….will not work if not mu.
Buddypress there needs to a be an update about this; even on this site there is an article that is out of date about themes and checking for compatibility but there is no update to it.
Questions: What makes a theme BP compatible? I looked at several themes that are and none have buddypress anything anywhere let alone a folder, so what makes theme buddypress compatible.
Is there a way to select a template to use JUST for buddypress? we have a site, been using the same wp site for a while, changing theme is not an option. How do we make it work with our theme?without bp legacy files.

Please help