how to allow a list collection to be a lookup to other subsite?
by doing so it eventually reduce the data duplication. For example, if you have a supplier contact, and you want to be a lookup for each subsite.
Create a lookup list from Home site.
1. create the list at your home site.
2. go to Site Actions -> Site Settings.
3. Under Galleries -> Site Columns
4. click on Create
5. give a column name.
6. Click on Lookup(Information already on this site)
7. Under Group section, you use existing group name or create a new group name. E.g: "Home Lookup Group".
8. As usual, create your lookup list refer from list collection and columns.
Setup a lookup list from existing site column.
1. Create a new content in any type or from existing content type.
2. Create lookup column with "Add from existing site columns".
3. Choose from the group you created.
4. click the "Add >" button from "Available site columns" to Columns to add".
5. Click OK to save.
