Is there a reason it won't accept 'fy nhad a fy nhad-gu'?
Yes - you have mis-spelt fy nhad-cu. It is mam-gu, but tad-cu
Thanks! I noticed almost immediately after navigating away from the page, but then couldn't get back to it!
Why isn't tad-cu accepted? Is nhad a north wales thing or is it used across the country, I live in south wales and have always heard dad and tad cu being used.
tad-cu and taid are both accepted for 'grandfather'.
Check that you have applied the correct mutation following fy.