Say W is a weekly series located in a weekly dataset, and D is a daily series located in a daily dataset

When in a daily chart and inspecting W.Date and D.Date I might see the following:

W.Date D.Date
...
05.12.2000 07.12.2000
05.12.2000 08.12.2000
05.12.2000 11.12.2000
12.12.2000 12.12.2000
12.12.2000 13.12.2000
12.12.2000 14.12.2000
12.12.2000 15.12.2000
12.12.2000 18.12.2000
19.12.2000 19.12.2000
19.12.2000 20.12.2000
... ...

Now if I add these two series together

Result = D + W

I'm getting a Result.Date similar to D.Date

However, when I'm adding it together

Result = W + D

I get a Result.Date similar to W.Date. BUT it should also be like D.Date.

This can be particularily confusing when program code checks on the date of the Result series.

QUOTE:
I get a Result.Date similar to W.Date. BUT it should also be like D.Date.

No, it shouldn't. The external series is synchronized to the primary series which serves as the "donor" for dates.

WealthScript Programming Guide > DataSeries > Accessing Secondary Symbols > Secondary Series Synchronization