I Live In A Lease Hold Flat And The 2 Flats Above Me Are Owned Equally Owned By A Brother & Sister.

[recordman]

As equal Landlords they do not agree to a parking dispute regarding my car. He is quite happy with the arrangement she isn't. Her boyfriend who lives in one of the flats(a tenant)is the troublemaker. Am I correct in assuming that both must agree as the sister is threatening legal action against me? This situation has been going on for a least 7 years. any good advise will be most welcomed

[ToraToraTora]

Can you be more specific about the issue. She is threatening legal action thus she believes you are parking somewhere you are not allowed, her brother seems not to mind. More detail needed.

[ladybirder]

Have a word with the Leasehold Tribunal. They are very helpful.
https://www.gov.uk/leasehold-property/leasehold-disputes

[Peter Pedant]

easy one
first of all - what does the lease say ?

if the lease doesnt say you can park - basically you are screwed.
if he wants to grant a right and the equal landlord does not then I think you are screwed as well.