You can manually add funds to your trips' unallocated funds and include a donor's name as well as amount and allocation type.
From your trip's Admin tab, select Funding.
When you click on the Add Funds button, the new popup will appear with all of the options available.
1. Enter the Donor Name
2. Enter the Amount
3. Select the Allocation Type
4. Click Add Funds and it will be added to your Unallocated Funds Total.