Trustees may apply not more than half of the presumptive or vested share of the capital held in trust for any person (infant or adult) for his advancement or benefit (including maintenance) on the following conditions:1. The trust property consists of money or securities or property held on trust for sale;
2. No advance can be made to prejudice any person with a prior interest, unless that person is of full age and gives his written consent;
3. The interest may be vested or contingent;
4. The advance must be brought into account on his becoming absolutely entitled;
5. The power may be excluded by the trusts instrument S .34.