I would think that if you moved the clutch now she would not sit on it. They often build up a very large clutch before they start to sit, although it might be best to reduce it to 12 so she can cover them all more easily. It could be that it's an old clutch which has already been abandoned - see if she adds another egg each day. Our free range hens do this every year, most annoyingly. Some eventually appear out of the undergrowth with anything from one to 12 chicks. Last year a Scots Grey did this and we were unable to get her into a house before nightfall (she had gone completely wild) - by the morning the whole lot had gone, dinner for the fox. But we have nearly always found it impossible to move the clutch and keep the hen sitting. When it has been successful is when we have waited at least a week for her to get really settled into brooding, moved the whole nest no matter how makeshift or manky then shut her in a very small broody coop. Once hatched, we usually end up letting them raise the chicks in the polytunnel, being the only place which is safe from the sparrow hawk, corvids, stoats and so on. Disastrous for the veggies of course

Our New Years resolutiuon each year is to build a proper pen for raising chicks.