Well, different age but mine got supper instead of BT milk at 12 months.
We did the supper with a cup of milk about 1 to 1.5hr before sleep. So the supper was finished before our BT hour began. DS's WD included 20 mins downstairs, followed by potty, teeth, bath, dry, pjs, potty, song sleep. It felt like the supper was just before bed but actually there was still time for the food to go down and the wee to come out.
I usually avoided fruit as I felt it would be too acidic for before bed. So bread and butter, toast with butter or pate, crackers, left over dinner such as veggies. Mine doesn't eat porridge but it may make a nice supper. Always a cup of milk which I did not limit, like I said there is enough time for him to double wee before BT, cup of water by his bed in case he is thirsty. He was night dry at 2.5.
The other things you could do is offer a cup of milk the moment she wakes up so she doesn't have to wait for breakfast. Mine has always had a morning milk rather than BT milk, he still does now (4yo). If he is particularly hungry, like a GS he asks for a banana with his milk so that he can eat immediately and still have breakfast later.
(he hasn't had a supper in a year or two I think, gradually just wasn't interested)
