Ok.

I tried taking the approach of setting a variable string to try and dynamically set the path and file name (I could see a variable for the name), the I used something like @[PackageFileLocation] + "\\PackageA.dtsx" , but BIDS just kept throwing errors.

So i've taken a step back I am looking at using the package configuration option.

This would work in terms of setting the path in a live and development enviroment, but main issue I can see here is that probably have to change the file locations in the configuration table (i'll be using an sql configuration table) when new packages are published to a live enviroment. of course this will mean amending all new package connections strings in the live enviroment, after the first run, or copy from dev to set them up and then amend?

Is this the best way of doing this ??? This just all seems way more complicated than it should be in this day and age?