Can you borrow from "designated funds" to pay other bills, and then replace the funds later?
You run a serious risk in using donor restricted funds for a purpose different from the purpose designated by the donor. In Pennsylvania, the CEO of the Allegheny Health Education and Research Foundation was convicted of misappropriation of entrusted property and sentenced to up to two years in a halfway house for using funds designated for scholarships and research for the general purposes of various hospitals before they filed for bankruptcy. At the very least, you run the risk of civil liability for breach of fiduciary duty, especially if you can’t pay the money back to the designated fund. It may come out of your own pocket.