time-lapse for ERT measurements conducted with different models of Terrameter

[SeismicStorm]

Hello,
I have a question related to Res2dinv data processing for ERT. I conducted the measurements three times at the same profile and during stage 1 of my research I used Terrameter LS, while during two next stages I performed the measurements using Terrameter LS 2.
It would not be much of an issue if later I haven't decided I would like to process this data using time-lapse tool available in Res2dinv.
I encountered a problem because I the numbers assigned for electrodes arrangement seem different for data obtained with Terrameter LS than with Terrameter LS 2.
I had no issue with preparing data for time-lapse for stage 2 and 3, yet when I wanted to add stage 1 to the whole thing, turned out no data sorting helps.
Is there any way to use time-lapse tool, for data obtained with different instruments? Or any way to convert data so it works?
I'd be really glad for any help.