As some contributors have said, the first step is to address the issue on the ground with the manager. They seem to be reasonably well-resourced, so see if they can’t simply rotate children in groups around the various spaces, activities, etc throughout the day or week.
The manager may well believe s/he is doing the right thing in terms of what is appropriate for the particular groups of children in terms of their current needs. Personally that’s not an approach I like, but ironically it's right down Ofsted’s street.
Parents have opportunities to contribute when ofsted inspections are conducted.
Whilst I agree this set-up might have an adverse effect on children’s development, I don’t think we know enough to assert that quite so strongly as some of the above posts have done. I think you’d have to be on the ground and consider the bigger picture, starting points, learning outcomes, individual children’s interests and abilities, etc. All of which is what Ofsted inspectors are at least supposed to do at routine inspections.
The attitude that is most unhelpful is typified by an earlier comment of "move and report to Ofsted". This sort of thing is all too common on NM, but you don’t solve problems by complaining to Ofsted about every last little thing.
I do wonder if most people are confused about the actual purpose and function of Ofsted.