This is a follow up question on this thread
I have come across the following relationship in a CTD curve bootstrapping routine:
$$\frac{DF_{XXX}^{CSA.EUR}}{DF_{EUR}^{CSA.EUR}} = \frac{DF_{XXX}^{CSA.USD}}{DF_{EUR}^{CSA.USD}}$$
where $XXX$ is a generic currency (e.g. CAD) and $DF_{XXX}^{CSA.EUR}$ denotes a discount factor collateralized in EUR, etc.
Would some be able to explain why(and under what conditions) is this true?