SMS and SCCM Overlapping boundary

The overlapping AD boundary between SMS and SCCM  can be managed peacefully, but requires that the security setting on AD System container have separate set of security for SMS and other for SCCM. By doing this SMS client will see only they MPs and DPs and vs SCCM client will have only SCCM MPs / DPs returned from AD. This is not supported by Microsoft since it can lead to unpredictable results if some of setting isn't set right. So, doing Migration SMS 2003 to SCCM if AD site was used as the site boundary, we have to brake it to IP sub-nets or IP ranges to separate the SMS and SCCM infrastructural.

How SMS / SCCM Client get DP

tepFromAction
1ClientSends a content location request to its Management Point (MP)
2MPThe search for Distribution Points (DP’s), with the content, starts in the client’s current site. This can be the client’s assigned site, secondary site attached to it, or a site to which the client is roamed. When the content is not available here the search goes to the assigned site.
3MPThe list of found DP’s will be sorted. When a protected DP is found, where the client’s boundary is included, only this will be returned. If there is not a protected DP found it will return a list of non-protected DP’s that host the content.
4MPThe remaining DP’s on the list will be marked as local, or remote depending on the boundary that you have connected to it.
5MPThe list with available DP’s is send back to the client.
6ClientTries to connect to the DP’s (of the list) in the following order, first for the local DP’s and then for the remote DP’s: Same IP subnet, Same AD site, remaining. In every category the client prefers DP’s with BITS enabled.

So, you have to tell your MPs which boundaries you have and connect them to your DP’s by protecting them.