does anyone have any experience of working with another childminder in one house? How this affects the number of children they are allowed/ how they managed contracts ect.

I haven't done it but knew 2 who did - the house they were using was a fair size so each childminder had there original numbers to work with all contracts with parents remained with the individual childminder.

They were still 2 individual businesses -

Carolyn and I work together (either at my house or her's) at least 3 days per week, Ofsted are aware of this and were ok with it. We have separate contracts and are separate businesses . We are in England, so not much help in Scotland , but hopefully someone with more knowledge will be along with advise .:)