Hi Robinou,
I still couldn't figure out exactly what kind of manipulation on worksheets you want to achieve.
But, if you want to (two) worksheets simply column-wisely "join" using the Time as the key
so that the each Y datasets can be shifted properly with the corresponding time, you can use
wjoinbycol command from the Script window.
http://www.originlab.com/doc/X-Function/ref/wjoinbycol
For example, the following command produces the new worksheet, Book3 from Book1 and Book2:wjoinbycol irng:=([Book1]Sheet1,[Book2]Sheet1) condition:="[Book1]Sheet1!Time=[Book2]Sheet1!Time" ow:=[<new>]<new>

Hope this suggestion gives you some hint.
--Hideo Fujii
OriginLab