Using different datasets to the different timeframes would be exactly the solution I am looking for. Could you give me a clue how can I achieve this?

If I understand you well, I need to do the following, by two different scripts (because of the different BarPeriod)



And everytime I start trading, I need to first run the loader to download the H4 bars as datasets.
Am I correct?

I see the dataset help page,
https://zorro-project.com/manual/en/data.htm
but still can't figure out how can I use datasets it in the same way as backesting as realtime trading, because I need to update somehow the H4 dataset time-by-time, during the backtesting and also in the trading

Suppose your H4 data is in column 1 of dataset H, then

var PriceH4 = dataVar(H,dataFind(H,wdate(0)),1);

So a possible solution:

When I start the "trader.c" script (BarPeriod = 1), in it's INITRUN it executes another script, let's call it "loader.c":
The "loader.c" (BarPeriod = 60*4) does nothing else but downloads/saves the H4 bars to datasets. It should read a parameter somehow from the "trader.c", because it should work the same way as I run the "trader.c" as Test mode (via an old StartDate), as with Trade mode. So it reads the mode and the StartDate, it goes through the LOOKBACK period, then saves the datas of assets, then imediately just quit(), giving back the processor to the "trader.c" script.
Then the "trader.c" script loads the assets' H4 datas to vars, then uses it to the Testing or the Trading session. And of course, the whole process mentioned above is just for start the testing/trading - after start, the "trader.c" script should take care of updating the H4 vars in the future, everytime a new H4 bar arrives.

And this is the only way I can use exactly the X amount of H4, and X amount of M1, with avoiding the unnecessary bar loadings.

Petra, did you mean this process, or am I overcomplicating the whole thing?

Yes it sounds complicated. I would not use 2 scripts but only one. Load the data at start with assetHistory in a dataset. You'll get H1, not H4, but you can then simply use only every 4th record.