Breastfeeding/Formula

I'm EBF my baby, but was considering giving formula at night before bedtime but looking for advice first.

My baby likes to cluster feed/comfort suck every night to fall asleep. Some night it takes a few tries before she is good to sleep in her bassinet (she will fall asleep eating, I put her down and she wakes up a few minutes later and we do it all over again). I'm wondering if I breastfeed and top her off with formula before she falls asleep if that will help with her going to bed more easily? Once she is asleep she does great! She is 12 weeks and has been sleeping through the night for about a week now.