Well, as I said there are so many Avern by the same name that we seem to keep going in circles.
The will of William for 1775 - he died in 1776 a widower,
gives the following names that we could make out for now until the hard copy shows up:
Children of late son William namely Thomas & John and their sister Amy (the grandsons were left the 2 farms in tenements??) [these 3 children seem to show up baptised in Shustoke, no mother's name was given, but a William Avern married an Elisabeth Fairfax in Alvechurch, where Clement and Amy [children of William] were both married.]
daughter Elizabeth & her husband John Haycock & "their children"
children of daughter-in-law Elizabeth -John & Thomas (am presuming that Elizabeth was William's wife as no other daughter-in-law in mentionned, and John & Thomas were mentionned prior)
children of son Thomas (not named), Thomas was made executor.
children of my son Clement: Thos & James, & possibly Susannah (Lawrence?) as well as possibly John who was to be found and provided for.
son Clement was left the farm, cattle, hay, implements, etc.
Your records indicate that the Malt House was built by Mary Ann's father, not Thomas' line. So the Thomas the younger in 1792 and his widow Mary in 1815 were Mary Ann's parents. Do you have any other info besides what you posted that would show any other family members at each of the times the Malt House was transferred?
Baptisms for Thomas Avern around the time frame we are looking at include the Thomas you mentionned in 1772, son of William & Mary BUT also include a Thos. Averon (sic) on 10 May 1773 son of Thos. & Elizabeth. This Thomas senior was William's son born about 1728.
Cemetery transcriptions show a Thomas Avern died September . . . . . . aged 58 and Mary his relice who died January 29 . . . . . . (8)3 years. Can you add anything to this to confirm if these were Mary Ann's parents?
The other Thomas died April 24th 1852 aged 76 years and his wife Mary Ann died Jan 8th 1870 aged 80 years (as per the transcriptions)