As far as Tregian/D'Oyley goes..., remember back in February that mark66 gave the following descent as probably correct:
2b. Elizabeth Dannett married Sir John Arundell
3. Katherine Arundell married John Tregian
4. Katherine Tregian married Robert Doyley
5. Martha Doyley married Bartholomew Tipping
This was in the Bartholomew Tipping thread. Mark also wrote: "ODNB does note that Francis Tregian's father John was of "Golden Manor, near Probus, Cornwall", which presumably is the "Gouldein" referenced in the Vis. Oxon. The estate was lost to the family with Francis Tregian's recusancy conviction in 1579.
Vivian & Drake's 1874 edition of the Visitation of Cornwall (p 275) contains some will extracts for the Arundell family which both makes it clear that Katherine Tregian nee Arundell was the daughter of Sir John and Elizabeth nee Danet (d 1564) and implies that she had other children: Elizabeth mentions "god-daughter Elizabeth Tregian" while Jane Arundell (sister of Sir John) mentioned "niece Mary Tregian":
https://archive.org/details/visitationofcoun00sain/page/274/mode/2up?q=tregian
These, together with the Vis. Oxon., seem good evidence for the descent from John Arundell & E. Grey to Martha, the wife of Bartholomew Tipping; the 1632 PCC will of Martha widow of Bartholomew Tipping names 'my fift sonne Mr Doyly Tippinge' ..."