I didn’t find anything new that would help us determine whether Scandalous Charles is the brother of the others. But 1625 is a solid birth year for him.
https://www.jstor.org/stable/1915677?seq=2#metadata_info_tab_contents page 152 “In the Northumberland Records (Book 2, Page 166) under date of October 26,1665, there is recorded “Charles Ashton aged 40 years or thereabouts deposes.” His wife Isabella also made deposition in the same year.” The wife’s name proves that this is the correct Charles Ashton.
I can’t find information on what he was deposing about, but people with a paid subscription to Ancestry can probably look it up online: https://www.ancestry.com/search/collections/genealogy-glh46544192/ Page 162 of this book is apparently where they have all the scandalous testimony about Charles and Mrs. Lyndsay.
Here’s the will of William Frizer, suspected father of Grace Ashton the wife of Captain John of Westmoreland county. He doesn’t state his relationship to anyone but his godson, but he leaves most of his property to the children and widow of Captain John Ashton of Westmoreland county.
https://www.colonial-settlers-md-va.us/getperson.php?personID=I0718...
“William Frizer, WC, chirurgeon, d. leaving a will dated 9 Sep 1677, proved 21 Nov 1677.
To Mrs. Grace Ashton, widdow, extx. my gold watch, all my debts.
Unto Prissilla Ashton, horse and mare. Prissilla shall give Henry Ashton the first mare colt.
Unto Henry Ashton, son and orphant of Capt. John Ashton 2000 a. of my tract of 5500 a. purchased by me of John Mathews. If he die before age 21, to his brother Charles Ashton. Unto Grace Ashton Junr. 500 a. of 5500 a. tract.
Unto Mary Ashton, 500 a.
Unto Sarah Ashton, 500 a. - daughters and orphans of Capt. John Ashton each 500 a.
Unto Thomas Beard sonn of John Beard my Godsonne, 2000 a. being the remainder of the 5500 a.
If he die to Prissilla Ashton. {WC DWP, 1065-77:346-346a}”