CGT On Property

I have a client who is giving up part of her share in a property which she currently owns 50% with her 3 daughters. The property is currently worth £600,000 and the daughters are adding a further £300,000 for renovation, when it is thought the property will be worth £900,000. My client wants to reflect the additional money being spent by reducing her share of the property. This will be so that before the work is done, her share is worth £300,000, and after it remains at £300,000. Effectively disposing of a 1/6 share to her daughters.

I cannot find anywhere a real answer to whether this is a disposal, and if so, of what. Her share of the property before and after will be worth the same.

Thanks for any help.

Roger
Roger Holman