Hi Ris,
Welcome to this Microsoft Project newsgroup
Project measures the %Complete based on the number of working periods
completed against the total number of working periods planned. The Duration
is just a measure of the working time between start and finish. Thus
Doration and %Complete are inextricably tied and you can't change one
without the other. (This, perhaps, is a good reason not to track staff
tasks within a project.) However, If you look at the % Work completed, it
could give you what want as it will remain correct irrespective of the end
date, provided the task is of Fixed Work type and changing the end date does
not introduce more or less work. That being said, it is not good practice
ever to insert start and finish dates as that is what Project is for - to
calculate the schedule for you. You enter the precedence link and the
Duration and Project will calculate the dates for you.
Another possibility is to create a hammock task that expands or contracts
with the controlling milestones - please see FAQ Item: 19. Hammock Tasks.
FAQs, companion products and other useful Project information can be seen at
this web address:
http://www.mvps.org/project/
Hope this helps - please let us know how you get on
Mike Glen
Project MVP