Property proportions

My clients are parents who purchased a 70% interest in a property jointly with their daughter who purchased the other 30%. The parents never occupied the property but it was solely occupied by the daughter. All three names appear on the mortgage and deeds and there is a trust document recognising this fact and that they will share in any growth in value. They are each responsible for their share of costs. However the parents let their daughter reside in the property rent free from the date of purchase (March 2001) to December 2005 although she paid a share of the mortgage. The daughter married in 2002 and her husband moved in with her. From December 2005 the property was let out.
Would readers agree that the daughter is the beneficiary of an implied trust created by the parents by virtue of the...