In ""The Oxford Guide to Heraldry" the authors, Thomas Wookcock, now Garter
king of Arms, and John M Robinson, then Maltravers Herald Extraordinary,
write on page 126:
'quarterings are acquired by the marriage of an ancestor in an unbroken male line with an heraldic heiress and may be borne by the issue of that marriage'and on page 128:
'A right to a quartering requires both descent in an unbroken male line and an heraldic heiress at the head of the line'I have included both these similar statements to underline that the modern account of quartering of arms is very clear on this matter.
This page is only to give you the rules of this traversing; the next page has the discussion of what consitutes quarterings. The college of arms has a unique way of drawing pedigrees which has the benefit of getting maximum information on the paper. If you are not familiar with this, get a print made of the file from the previous page or find the pedigree on pages 132 and 133 of the above book and use that to work through it as follows: