Hospitals may treat any 2 or more trust funds as a single fund solely for the purpose of investment, if such investment is not prohibited by the instrument, judgment, decree or order creating such trust funds. Unless ordered by decree, the hospital so investing said funds is not required to render a court accounting with regard to such funds, but it, as accountant, or any interested person, may by petition to the Superior Court or the probate court in the county where said hospital is located secure approval of such accounting on such conditions as the court may establish.