Cooling period between two visits on schengen visa

[Bhushan Shukla]

Hi, I am an Indian and moving to Finland for work. I want my mother to accompany to Finland for long term. However, parents are not considered as dependent as per "The Finnish Immigration Service". So the only option for my mother is to make trips on schengen visa.

So the question is: once she has stayed in Finland for 90 days, is there any cooling period before (a) she can apply for visa (b) travel to Finland again?
It would be great if you can share information source with your answers. Many thanks in advance!