This is something I just don't get.

I have a Child table with a repeating field, "Profile", with five repetitions. In the parent table I define a new field Total with five repetitions as Sum(Child::Profile). This then adds up all five repetitions for all the related records and puts the same number in all five repetitions of Total. But what I actually want is for each repetition of Total to be different, ie the first repetition of Total adds up the first repetitions of all the related fields. This is so basic! What am I missing?

You can sum individual repetitions of different fields IN THE SAME RECORD, but not of the same field across a relationship.

Perhaps something like this could work for you:

SumR.fp7.zip

Thanks comment. At least now I know I'm not going mad. The approach in your file won't work for me because I'm actually trying to display the Total field in the rows of a portal - so a summary field is no good. I'll have to switch to five separate fields. This seems a very odd omission by Filemaker, and the manual really obscures the point, which is annoying.

I'm actually trying to display the Total field in the rows of a portal

That seems very unusual. What is the real purpose here?

This seems a very odd omission by Filemaker

Actually, it's a very odd INCLUSION, having the aggregate functions deal with repeating fields AND related fields AND individual values - see:

http://fmforums.com/forum/showtopic.php?tid/191946/post/275459/#275459

Well I'll accept my usage is unusual. We're using Filemaker as a tool to calculate and present statistics - basically as a souped-up Excel. But if Filemaker defined sum in the way I expect, you'd be able to get the current result by doing sum(sum(child::Field)), so I think my approach is more flexible and therefore better!

:idunno:

Better than what? I only asked what you're doing, to see if there may be an easier way to do it.

Incidentally, if you put the summary field inside the portal, it will still work.