My husband passed away, need advice on his loans/debts

My husband passed away, he was in transport/trucking business based out of U.P. Now, we have 2 trucks under bank loan. I plan to continue running his business and have questions around that. My questions: 1. Can the trucks continue plying on the road without the succession certificate? I am in the process of applying for succession certificate and it will take a month but I need to continue running the trucks in order to pay EMIs. I have heard that in UP you can run trucks without succession certificate for up to 90 days after the death of Owner. 2. For one of the truck loans with IndusInd bank, we have a guarantor who is causing issues. He is asking me to sell the truck as he has vested interest & wants to buy the truck for less than market value. He says I cannot run the truck. Question: Can the guarantor legally stop me from plying the truck? As I mentioned I am in the process of getting the Succession certificate and after that, I plan to change the loan ownership to my name. can I change the guarantor at that time? Please advise.