Selling ex-family home....

15 years ago self, wife and adult daughter lived in and owned jointly (3 ways) a house (A). Mother ,who lived alone elsewhere became ill so all 3 of us moved to her house to help. We let our own house (A) some 10 years ago. Subsequently we inherited mother’s house and it became our main residence, again jointly. We now want to sell our original house (A)and understand that we must declare 1/3 each for cgt. subject to deduction (also a third) for time we lived there, is this so? Are there any other concessions beyond occupation time deduction and personal allowance each?

Hi,
Yes that is correct, for other allowable costs,
please see:-
CG15180 - Expenditure: enhancement expenditure TCGA92/S38(1)(b)
and
CG15250 - Expenditure: incidental costs of acquisition and disposal
Thank you.

As we bought this home 20+ years ago we no longer have record of purchase expenses.... but we did get environment search and local authority searches which we still have as proof, no idea what solicitor charged(no longer in business) so would there be an acceptable "ball park" estimate amount that would be acceptable to HMRC for cgt return? Cost was circa 115k.

Hi
Please refer here Report and pay your Capital Gains Tax and Tutorial

Sorry, you don't address the scenario where costs of buying are unquestionable, but invoices lost over 20 years ..... can we estimate?

Hi,
When you do not have receipts, you can use estimates as long as they are reasonable and  justifiable. You will also need to advise that you are using estimates and state why you have used an estimate and how you have worked out your figure.
Thank you.