I've been working on a MS CRM 4 project and found that the custom entities that we added displayed an 'Add Existing xxxxx to this record' button when it was not required and created a lot of confusion among the users.
Microsoft have said they will make this optional 'In the next release' but that is not soon enough for me!
After working through various ideas on how to solve this with Ian Crowther and Steve Vallance we came up with the following fix. Thanks also to 'Dynamic Methods' for this post about hiding buttons: http://dmcrm.blogspot.com/2008/01/hiding-buttons-in-mscrm-40.html
This javascript should be added to the onLoad event for the form of the entity where you want to hide buttons for the associated views of other entities. You then need to call the function HideAssociatedViewButton for each associated entity - passing in the name of the dataArea div tag and the title of the button you need to remove. (this can be found by using the IE Developer toolbar):
The original code snippet (version 1) can be found here:
http://blog.davehawes.com/page/Remove-Add-Existing-xxxxx-to-this-record-button-version-1.aspx
This version (version 2) has been updated thanks to the contribution from David Berry. His code splits out the hiding of buttons when an iFrame is loaded into a separate function. It also allows multiple buttons to be hidden which is very useful as well as allowing the function to be used to hide buttons in other iFrames as well. Many thanks David.