Is it permissible to return money stolen from one's parents in the form of monthly installments to help them until the full stolen amount is repaid?

Whoever stole money from his parents must return it to them immediately in a single payment if he is able. It is not permissible for him to return it in installments if he is capable of expediting the repayment. If he is unable to return the money in a single payment, he must return it whenever he can. He is not obliged to inform them of the theft; it is sufficient to return the money by any possible means, even if it is presented as assistance.