Historical data with no change in rule of time (say GMT)

 

Hi everyone,

When I convert data say M1 into different TF and then covert to say NY-time, I think I have to make sure that time rule of the broker is NOT changed so that the adjustment from H1 to H4 and then D1 is consistently correct.

I wonder which broker doesn't change their time

In case all of them change time in the past, can we find when that happen?

Thank you.

SCFX