All I know is that my initial, very valid, suggestion to use the valve on the meter was immediately invalidated when I found out your property is in Scotland.
David
It is entirely possible, more probably likely, that the cold feed to the bathroom is tank fed. To check open the basin cold tap and put your thumb over the spout, if you stop the water it will almost certainly be tank fed. Since the property has a combi fitted it will have had the cold feed teed from the rising main and the hot outlet connected to the original hot supply to the bathroom, typically a small cylinder often located above a cupboard in the kitchen.
Go round all the tiles in the bathroom & kitchen and poke the grout, you may discover that somewhere it is not grout but actually silicone or similar and the tile can be removed to access a valve. This is what I found in my flat here in Edinburgh, where kitchen and bathroom water enter the flat from opposite sides of the building.
This is what I'd do.....With the agreement of the neighbours turn off all the water......then see if you still, have a supply at your taps ...check all of them, if some of them keep running ......storage tank. If they all stop mains fed.
Shut your taps and again with their permission flat by flat see if turning the water off in another flat turns your daughters off. If that fails it's a case of finding where the supply comes in to your daughters flat...... trace the pipes back from each cold tap and follow the direction. ...your bound to find it eventually.
It's really not that hard ......where the supply comes in fit a new stopock if there isn't one ......and ask the previous owner !
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