Hun, if trying a DF means she doesn't EW and not resettle then I would give it a go, the NF should still continue to get later in the night YK? Or you could do the DF, then wean the NF if you think it's not needed.
My first never had a DF and woke at 4 for 1 NF. It's really about your preference but IIWM I'd give the DF a shot and see how the nights pan out for 3-5 days.
Our feeds for Z were dropped a follows
NF 7/8 mths
Mid arvo 9 mths (feeds were WU, lunchtime before pm nap, BT)
Breakfast 11/12 mths (switched to bottle before nap (lunch) and bf at BT)
Lunch 14/15 mths
BT 18 but we switched to a bottle as I was pregnant)