Confirming Isabella's family from her birth place on the 1891 Census after she married George:
George A Johnston 28, Grocer & La Merchant, b. Airlie, Forfarshire
Isabella Johnston 30, b. Collace, Perth
William Johnston 4, b. Dundee
Maggie Johnston 2, b. Dundee
Robert Johnston 2 Mo, b. Mains
Address: The Grange, Mains, Angus
And Isabella, just born, with mother Margaret in the 1861 Census:
Robert Millar 46, Farmer Of 190 Acres, b. Fowlis, Perthsh
Margt A Millar 22, b. Collace
Ann W Millar 1
Isabella W Millar 2 Mo
Isabella Waddel 82, aunt, b. Liff Forfarshire
Jane Anderson 14, FS
Henry Brough 18, MS
Jessie Doctor 21, FS
Address: 1 Flowerdale, Collace
Gordon, If you want to follow up on Robert Millar's estate following his death, there looks to be a will for him on SP:
Millar Robert 24/05/1899 sometime Tenant, Farm of Flowerdale, Parish of Collace, thereafter residing at Rose Bank, Balbeggie, d. 14/02/1899 at Balbeggie, testate Perth Sheriff Court SC49/31/176
Regards.
Monica