That is if the FST ID number for the MT4-FST_Expert attached to a EURUSD 15m chart was 55, the MagicNumber was to made 55 also.
Not necessary. Leave Magic as it is by default.
Then, if the FST ID number for the MT4-FST_Expert attached to a GBPUSD 15m chart on the same MT4 demo was 44, I understood that the MagicNumber setting for that chart would be 44.
Also it is not necessary.
Now aren't you saying that its MagicNumber should be 55, rather than 44, also??? Confused.
Just leave it default. You don't need to change it in most of the cases.
Expert_Magic must be changed ONLY if you run strategies on same symbol.
Examples: 5 strategies on: EURUSD M15, USDJPY H1, USDCHF 1H, EURUSD H1, GBPUSD H1.
Here you HAVE TO change the Expert_Magic for EURUSD M15 only, in order to separate it from EURUSD H1. For all other strategies you can leave the default Expert_Magic. (or to change the magic number for EURUSD H1)
Setting different magic for each strategy running on different symbols is not wrong but is useless.
FST Expert separates deals by the symbol. Expert_Magic serves to separate deals if more than one strategy runs on same symbol.
If you have two strategies on EURUSD H1 and USDCHF H1, FST Expert knows that positions opened by the first strategy are for EURUSD and the second strategy opened positions for USDCHF. So here we do not need to change the magic.
But if we have strategies running on EURUSD H1 and EURUSD H4. FST cannot separate the positions of the strategies only by their symbol. Here comes the Expert_Magic. We have to set different magic for each strategy since the symbols are equal.
For Connection_ID is clear. Each expert has unique ID number.