I want to exclude my client's ex-wife or ex-husband from being a beneficiary of the trust. Is this possible?
It is possible, and we can include this in the deed if you like (for an additional fee), although you had better hope you don't get back together!
It's also important to note that, although a person may be included as a "beneficiary" of a discretionary trust, they cannot actually benefit from the trust unless the trustee actively exercises its discretion to make a distribution to that beneficiary. Until such a point, all "beneficiaries" are more appropriately called "potential beneficiaries", or mere "objects", of the trust.
However, since it can be difficult to add beneficiaries to a trust after it has been set up, it is generally better to have the class of potential beneficiaries as broad as possible. Therefore, it shouldn't be a problem if an ex-spouse is included in the class of general beneficiaries unless there is a chance that he or she could become a trustee or appointor of the trust.