Have the nursery given a definate no yet in relation to taking Isla on the bus too? I took Hannah on the bus on one of Matthew's trips when she was about 2-3 months and they didn't have a problem with it, although all places are different. When she needed fed I just carried her and breastfed her whilst walking about. I was a bit worried Matthew wouldn't get to see everything but to be honest he was quite happy to follow the rest of his group rather than stick close to me, and he knew I was there and could come and get me when he wanted to show me something.
Hopefully they will let you take her too and you can be with both of them. I personally feel that mummy is the best person to go with their child and I've always tried to be able to go with Matthew on outings; his sure start group and now his playschool know that wherever I am Hannah always comes too

They probably think I'm really awkward and fussy!
Though if they won't let you take her, he probably won't mind too much if his auntie goes as he'd likely be running about with the other kids anyway and not sticking close to whoever is with him, would he not?