I've added what I can to her biography. Looking at the dates and the details in the heralds' visitations of Cumberland, together with various Surrey histories, I now suspect that she is more likely to the sister of Oliver Sandes (Sandes-39) and daughter of William Sandys (Sandys-58). To link all this up, it would be necessary to merge Sandes-39 with Sandys-68 and Sandys-26 with Sandys-91. I'm going to propose these and see what happens.