Hey there, I agree with your first point for sure.
I think the simple solution would be to continue running 7 EA's, each on its own chart, and set Max Number of Positons to 1 in each EA input tab. This allows SB's code to manage each pair symbol separately without having to do any coding.
Regarding one big EA, if I follow you, you want one trade for each set of trading conditions (from each old EA respectively) for a total of 7 trades using the new EA. I think Max Lots, or Max Number of Positions for that matter, are magic number related--counting lots or positions will not help you limit your single EA trading conditions without editing your mql code.
There was a recent request posted regarding "one trade per day," and I think your coding would be similar. Note, you need SB Pro for this. You would have to declare 7 new global variables, say
cond_1_trade,
cond_2_trade, etc. and assign each a default value, say
0.
Within each set of trading conditions, you would add a condition, say
cond_1_trade==0.
Within the operator(s) following each set of trading conditions, you would add
cond_1_trade=1.
So when the first trading condition enters a trade, it also reassigns a value of 1 to its own variable, negating further trading under this condition. Do this whole procedure 7 times and you should have mutually exclusive trading conditions--remember, each variable name must be unique. If your EA buys and sells, you'll probably do this more like 14 times.
The real problem is getting the values to reset back to 0 at order closure. The current version of SB cannot dynamically manage orders on an individual basis, so the code to edit is not present. You would have to build this from scratch by uniquely identifying each order at entry (via magic number, etc.); and then selecting each order individually via OrderSelect; and finally closing the order via OrderClose. If you choose this route, you can omit the variables I mentioned previously and use OrderSelect to limit your trading conditions as well. Of course, the crude but easy way out here is to simply let SB close everything at once at some condition and restart the EA manually.
Personally, I would opt to run 7 EA's!
And regarding 2 accounts, I cannot log into more than one account simultaneously on one MT4 installation. So I would have to say that unintended communication between EA's running on separate installations of MT4 would be extremely unlikely.