Has anyone got any tips on how to encourage a 3 month old exclusively BF bub take a bottle of EBM?

I tried a friend offering it and DP when I knew she was hungry but she just wouldn't take it.
I also tried two different teats but it didn't make a difference.

I have a friend due to birth her first baby in a few weeks and she has asked me to be her support person. If it is long I really need to have DD fed while I'm at the hospital. I'd also love the odd nap or sleep in too

Any tips will be very much appreciated