Praise be to Allah.
We put this question to our Shaykh, ‘Abd ar-Rahmaan al-Barraak (may Allah preserve him) and he replied:
It is sufficient for him to spend on them with the intention of paying off what he owes them, and in fact he will have been spending on them from their money, and he does not have to tell them the real situation. End quote.
For more information, please see the answer to question no. 129779.
And Allah knows best.