how would i go about getting betfair to add "will Tiger win another major in his career" market?

I guess you just phone the helpdesk, but not sure it would be to popular a bet as it could tie up funds for years, unless you know Tiger is about to retire maybe, there is the  market of how many majors tiger will win an a year by year basis up tho.

I have a bet with a friend that I will live to see her 50th birthday, good bet for me but she as not twigged to how she will get paid yet.

can't see betfair putting up a market.

You would need to be prepared to wait years. Its possible he will still be playing majors regularly for another ten years and turning up at the masters when he is tom watson's age

deffo a market to discuss on the forum rather than tie up funds for 20 years where inflation
would render bother sides of the bet poor value

both