Qitzur Shulchan Arukh – 65:27
A Jew who lends a non-Jew against a collateral with interest of such-and-such a month, and afterward the Jew goes to his friend that he lend him the money on this [same] collateral, and he takes on the interest from today until the final payment date, it is permissable. However, if the first Jew already combined the principal and interest [repackaged into one payment] for the entire duration of the loan [to be paid at the end] then it is all like the Jew’s capital, and it is prohibited to borrow against this collateral from his Jewish friend with interest, because it’s like he gave the interest from his own pocket.
In the previous two laws, we saw that as long as the Jew in the middle has no risk exposure, another Jew can use him as a proxy borrow money from a non-Jew with interest. Here we see another limitation — the interest has to match the currently existing terms of the loan with the non-Jew. If the terms changed in a restructure, than the interest paid between the two Jews constitutes a distinct deal, and is prohibited.