Putting Toddler DD Upstairs Alone

[Fantababy]

Our house has two upstairs and two downstairs bedrooms and currently DH and I are downstairs with 9 month old DD in with us and 2.9 DD in the other downstairs room. We'd like to move DD2 into her own room but as neither girl is a particularly good sleeper we can't put them in together so we're going to have to move DD1 upstairs to a room of her own.
Obviously we'll decorate it for her, and we've told her she'll be getting a new room upstairs but her being upstairs on her own, when she's so little, just doesn't sit right with me. Is anyone else in a similar situation?
We're at the point where we're waking DD2, and she us, so we're going to have to make some kind of change, and, either way, someone's going to be upstairs, but I just feel funny about it.

What are your concerns about her being upstairs ?

It has been asked on here a few times if it would concern people to have their dc on a different floor to them (in a 3 storey house), and, overwhelmingly the replies are, that it would be fine.

You will still hear her, if she cries out - but if that were a concern you could use a baby alarm.
You can have a stair gate either at top of the stairs or on her bedroom door if you don't want her to be able to get to the bathroom.
Or, you could leave her where she is and put the little one (who would presumably still be in a cot) upstairs.

I know. There is no logical reason for it at all. We've got video monitors and will put one up there with her. I keep thinking if there's a fire she's up there on her own but there is a smoke alarm. I know it's irrational, but it feels funny having her so far away from us.

I'll not put DD2 upstairs as she's still breastfed so want to keep her closer. I just wish they'd both sleep so I could put them in together, but I know they'd wake each other up.

I live in a 3 story and have 2 top, 1 middle and one ground floor bedroom. The thought of sleeping downstairs by the front door just felt odd to me so that was made into a man cave. Dd wanted the middle floor so she was by the bathroom and next to the living room so she could come and go as she pleased without stairs to contend with. So that's the room she got, I sometimes over think even now 2 years down the line about if we had a break in they'd get to her first etc but then I rationalise my thoughts and all is well. It's strange at first but now it's the norm.