I'll start the topic with reporting of new behaviour of FXCM-GBPDemo01 - Forex Capital Markets, LLC server.

When we have an aggregate position (position consisting of multiple positions in one direction as result of adding) and modify SL or TP, FXCM modifies all open orders automatically when send OrderModify to the first open order.

Normally the Expert cycles through the open orders and OrderModify each if them one by one.
As result of the new behaviour, OrderModify returns false and LastError = 1 (No error) for every attempt for modification after the first. This leads to multiple errors in Expert.

To fix this issue, I added check if the required new SL and TP are equal to the SL and TP of the open orders. If they are equal, the Expert do not attempts to OrderModify.

In the case where OrderModify returns false and LastError = 1, the Expert checks if the SL and TP are not already changed and if they were, OrderModify is marked as "Checked OK".

The attached Expert "MT4-FST Expert v1.11 Log.mq4" has the word Log in his name because Write_Log_File external variable is set to true.

EDIT Expert removed. Newer version attached in first post.

Please post the server names. I'll try to reproduce the errors. It seams there are some specifics to the broker server settings.

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You  can see the expert settings guide here MT4-FST Expert Options

This a loose possible X-factor, but perhaps jgp has a demo account for US residents? For US residents, the regulations say you cannot have specific stop orders for specific open positions, they have to be closed First-In-First-Out. FXCM implemented a "summary" stop for all open orders at a single stop exit price to follow these regulations. This might explain why changing a stop order modifies all open orders automatically.

If this is already known, or isn't exactly the problem jgp is having, please disregard, just mentioning in case it's not a FST-MT4 bug but the way the broker works.

A newer version of the expert is attached to the first post.
- Improved log messages,
- Sets trailing stop if Stop Loss is changed with more than 0.00001 with 4 and 5 digit brokers and 0.01 for JPY.
- Puts expert magic number in the log file name.
- Maximum length of log file is limited to 2000 lines (set in variable in the expert code). When the log file reaches the limit number of line, the Expert opens a new log file. This is done because reports that MT4 goes slower when works with long files.

At least two atta-boys Master Popov. Don't seem to be getting unwanted additonal entries [Winner or ADD FST strategies attached to FXCM or Alpari charts] with the latest FST-AE, but too soon to tell whether we get the additonal entries we want and should get as per FSB backtesting.  Many, many thanks for at least stopping the unwanted multiple time/price additions.