Manual Sharing lets you add the items directly from the application to the restricted domain. When you want to share some of the items with the users in the restricted domain (as they have admin defined access i.e. limited access), simply select the items and share with the restricted domain by going to the Actions drop down and selecting "Add to Domain" option. Also you can remove the those items from the restricted domain anytime by going to the Actions drop down, but this should be kept in mind that the items that been added to the domain using manual sharing only those items can be deleted from the domain using "Remove from Domain" option. The items added to the restricted domain using some other methods cannot be deleted using "Remove from Domain" option. Sharing of items can only be done by the administrators. 
To check the existing items in a  particular restricted domain, select that particular domain from the drop down present at the Top (as highlighted in the Image below, which has Show All in it by default ).

For the purpose of sharing/adding the items to the restricted domains manually follow the instructions below:

1. Go to the application who's items you want to share in the restricted domain.

2. Select the items those you want to add to the restricted domain.

3. Select the Actions drop down from the top, that gives you 2 options one is to add the selected items and other is to remove the items.

4. Go for Add to domain, which further lists the restricted domains.

5. Select the Domain to which you want to add the items. The items will get added.

Go to the next Article: Rule Based Sharing