Sorry for the delay. I do not believe there is a way to indefinitely pause a sequence once all the samples have been completed so that the user can then append more samples to the end of the sequence.
You might be able to accomplish what you want by using the Queue Planner. Here is a brief tutorial video on the Queue Planner: OpenLAB CDS Chemstation tutorial: Queue Planner . A new feature to OpenLab CDS ChemStation rev C.01.09 which is not discussed in the video is the ability to insert or append custom commands. These commands can be used to shutdown the pump in between sequences if needed.
Hopefully this helps.
I don't think there is and easy way to do what your asking for but I think there are 2 different ways to kludge something together. Like ryoboyle suggests the Queue Planner is probably easier (The Partial Sequence option also allows for some interesting sequence control).
If I understand your question correctly you could make a sequence for your first set of samples then add a (fake) sequence to load a standby (low flow) method or some custom commands and then a pause. Every time you add samples you would make a new sequence then standby then pause and add them to the Queue Planner. This should work (I Think).
The only problem is that every sequence will be in its own container so you'll need to add the separate sequences together and reprocess the sample runs. I'm assuming you have a custom IR summary report that needs to be generated which is why you wanted to continue a sequence. When you create a new result set all sample data, method data and reports get grouped together in a new directory.