Shannon family with mother's name Margaret

Hi, looking at old queries and cannot find baptisms to suit all the children, remember not all churches have records back that far, assuming Roman Catholic as we use church records at that remove, without a fathers name it is difficult to be sure anyway, a search for Margaret's baptism plus or minus 1 years brought back 4, could find no records for a Hugh or Rachel and Patrick is also common.

There is a site here where you can check surname distribution at various times, free to check but subscription site. 

https://www.johngrenham.com/surnames/ ;

On the off chance it means something, Shannon is a variant name of Gilsenan also, it is is a thing with some names in Ireland but I checked it also.

Regards

Pat