Sorting a Gantt chart with multiple rows by date

Hi everyone,

This one should be a nice one for the experts. Attached please find an example file.

The file is based on a Gantt chart and each project has 4 rows that need to stay together.

I would like to be able to sort the various projects, based on different type of criteria:

1.) project start data (advertising date)
or
2.) project leader and then by start date

As you can see the problem is that I am trying to sort data but the four rows always need to stay together in the same order.

Now, the solution I had thought of was to create some hidden columns, one numbered with:

1
1
1
1
2
2
2
2
The second one with:
1.1
1.2
1.3
1.4
2.1
2.2
2.3
2.4

Then, when applying the sort mechanism based on these columns, the data would be sorted in the correct way.

The problem here is though that as there might be different people working on this file, these numbers might not always be replicated correctly (copying and deleting of rows for example by unexperienced users).

Is there any more elegant way to do this sorting of multiple rows? Besides, I also have merged cells which make life more difficult, but I can remove these, if this helps to get the problem "sorted" ;-)


Thanks a million!
Titus