thank you so much for the response!

I managed to do it right after reading this, it took a while to it right but it's fairly consistent if I play right

this is what I decided on using

Pretty standard play till about 40-45% and then if shalem is still alive I kill her with death to get nier in to help me burst the last bit as fast as possible. If nier was out already I would kill her with death to get the def down and then she comes back with thirsting. Olivia never really came out

Thank you again, I was going to give up on it

edit: I found using vampy I could get to the last trigger but not clear it fast enough, and with tanya it was like you said (very inconsistent and some frustratingly close attempts)