Dates are hard to nunderstand back then.In most cases they are only estimates
of when they lived.That is why a son born in 1100,his father may be listed as born
1120.There names will lead you to the father.You will see Ap,Verch,The name
after would be fathers name.Google has a good explanation of Ap,Verch Etc.
You are in a tough time.You can figure it out.Best to read research hints for