Let’s have a look at the relevant terms. Clause 8.3 from the terms and conditions
8.3. On receipt of a satisfactory application form British Airways shall at its discretion issue to the Nominee a discretionary Silver/Gold Partner Card which will be valid for a minimum of 12 months from the date of issue. For Nominees who are existing Executive Club Members, the discretionary British Airways Silver/Gold Card period shall begin from the date of acceptance by British Airways of the Nominee and last until the Nominee’s Membership Year End date and for the 12 month period thereafter. For Nominees who are not existing Executive Club Members at time of nomination Silver/Gold Cards will be valid for a period of 12 months from the date of acceptance by British Airways of the Nominee.
Membership Year End means the expiry date on the Membership Card;
so from date of acceptance (i.e. the day you nominate) until membership year end (30 September 2019) and for 12 months period after (to 30 September 2020). I am not sure there is much ambiguity there.
[EDIT: I agree btw the reference to card expiry date isn’t helping, but it’s just a poorly defined term. The intention with the cards in your example has always been very clear.
I am not sure what to suggest, if you want to complain and think she is entitled to 2021 then you can try but I think you are wasting your time. Partner cards giving status for over 2 years would be contrary to what has happened for many years so i am in no doubt BA are not intending to do that.]
Fitch’s issue relates to when you nominate someone in the short period between end of membership year and card expiry, and they are only giving cards for about a year then, so it would be like if you nominated your daughter on 15 August 2018 and they would only give her the status until 30 September 2019.