Receiver Rex ? Assist / Vario and Height information

Hello together,
there seems to be no possibility to set the relative height to 0 bevor start. And also it is not possible to do a correction to the absolute height.

In my special case the absolute height differs round about 50m +-, depending on the air pressure.
The relative height is mostly in a range of +-3m. Thats a liitle bit too much for DLG flying.

It would be great to be able to reset the relative height with an switch and also to do an correction of the absolute height by the 3D function wheel.

Thanks a lot for reading and hopefully to send an solution.

Michael