Transferring data from form to form when starting new record

[JFo]

OK so my situation is a simple 1 to many relationship where the main form has the primary key and the secondary input form needs the foreign key to be passed to it to link the 2 tables.



Say for example 1 Site has many sections (Plants). The main menu form can therefore select the Site and filter to another combo box containing the plants that are attached to that site. The user can then either edit the plant or add a new plant record linked to the site.

I have figured out how to edit the plant attached to the site using a macro that opens the form Plants with the site ID passed from the main form however when I want to enter a new Plant I still need the site ID passed to the Plants form however using the following code

DoCmd.OpenForm "frmPlants", acNormal, , , acFormAdd

It simply opens the form as a new record and therefore will not transfer the SiteID

No doubt this is not the hardest thing to do I just can't work out how to do it

I have seen somewhere using code similar to this

stLinkCriteria = "[SiteID]=" & Me![SiteID]
DoCmd.OpenForm stDocName, , , stLinkCriteria

may help me but I can't seem to get it to work

Please help

Thanks

[JFo]

Private Sub cmdAddPlants_Click()
stLinkCriteria = "[SiteID]=" & Me![SiteID]
DoCmd.OpenForm "frmPlants", acNormal, , , acFormAdd, , stLinkCriteria
End Sub

Ok tried many variations of this code, if someone can let me know if I am on right track would be awesome, cannot seem to find SiteID from combo box