OpenDoc issueS

I'm not sure if this is an issue or there needs another function call I'm not aware of ?

When I use OpenDoc, say OpenDoc6, to open a parent document such as a drawing and use it again to open the document's child, its part,  I got error 128 "file already open"

Seems like OpenDoc opens all the children documents in invisible mode? is my guess correct? Duh... Use ActivateDoc3 to wake them up

Thanks

EDIT: There is another issue with OpenDoc6

if I run OpenDoc6 with SW2017 to open a file which was saved in SW2016, then SW2016 is launched for the file ?

SolidworksApi macros