Is it permissible to give the remaining checks to the sponsoring partner who has not yet received his dues, after a dispute over the division of losses in a company and the separation of the partners?

You must hand over the checks or tear them up with the engineer's knowledge upon receiving your money. It is not permissible to give them to the guarantor. If you fear the engineer will procrastinate with the guarantor, advise him without using the checks deposited with you. Sheikh Al-Fawzan has issued a fatwa (definition) stating that it is not permissible for an accountant to take money from an employer and give it to the wronged party; rather, he should advise and assist without disposing of the entrusted money.