Vermögensverwaltung is indicative of an organization, as in Trust Organization, as per the usage of verwaltung, so this is probably incorrect.
Vertrauen has to do with the noun-form of the English verb trust, and not to do with finance.
I looked up double-taxation (Doppelbesteuerung) on wikipedia.de, and found that it seems as though it does not apply to trust funds, which are Treuhandfonds.
This idea of generation-skipping in order to avoid double taxation appears to be an American and British problem, and as such the term does not translate to German, so I would probably avoid it, unless you decide to come up with fictitious reasoning for it. -- it appears that I am incorrect about this - refer to Olaf's answer for more detail.
In cases like this, where terminology doesn't directly translate, it is usually better to describe the object in question, when translating it to German. You could, for example say something like, "A trust fund designed for the grandchildren to inherit in order to avoid granting rights to the children..."
Another potential way to put it is Geschlossener fonds, which is a closed or locked fund, which according to http://www.investorguide.com/article/11813/generation-skipping-trusts-and-why-they-are-advantageous-igu/ is pretty much what a generation-skipping trust fund is. Though I'm still not certain that the usage is correct.