Living trust amendment

I have 3 beneficiaries and two have children. I'm leaving everything equally with a portion of the parents share to go to the respective children. The third beneficiary however is not mentioned by name but referred to the "children herein" I feel she should be mentioned by name. Can I personally amend this trust?

If you have any significant legal document, and a revocable living trust is certainly one, you should not amend it yourself. You really should have an estate planning attorney (not a general practice attorney) amend it and supervise the signing. There could be a range of issues you might miss. Even if you didn't miss anything the formality of an attorney supervising the preparation and signing will make it more difficult for someone to challenge the validity of the document, and less likely for their to be mistakes. Its a great idea for you to understand the document and planning to keep costs down and be proactive, but crossing the line of doing your own work is not really advisable. Do you need a companion pour over will? Should the agent under your power have rights to fund the trust? Modify it? Have you funded the trust? What procedures does your state require for a living trust to be valid? These are but a few of the many questions your lawyer may help you address.

As for your comments on who is named it is hard from your question to discern what is being done. It sounds like you have three named beneficiaries. Let's assume that they are all children for simplicity. Two of your children have their own issue (children), one does not. You want each child's family line to inherit a third, and of each third, the grandchildren will receive something directly on your death. If that is correct you still need to decide what happens if a child predeceases. Should that deceased child's share go to that child's issue? If all the above is correct, you may leave a third of the residuary to each child, and divide each of those thirds into two parts, with one part to the child and the presumably smaller part to that child's issue. Even for the third child you might use the same structure in case the third child has children or adopts.

As for your question concerning names, the answer can vary. The names of beneficiaries are generally used in order to be precise. However, in some instances bequests are left to a class of beneficiaries. Example: I give and bequeath $100,000 to be divided in equal share to my then living siblings". Siblings is a class and can be used without names (but that can create issues as well).