Legal rights waiver in writing under will - scotland

[EXECUTOR1]

As far as Scots Law goes, I am aware of legal rights of spouse/ children as well as their rights under a valid will. As a spouse and executor, is it wise to write to the children to request if they are waiving their legal rights? Proposed will is split equally between spouse and 2 children (1/3, 1/3, 1/3). The children are step-children and I am trying to prevent problems with them in executing will. Many thanks