Transfer at FRA
 

On my outbound, I plan to spend the day sightseeing in FRA before catching my flight to JNB. However, on the return, I plan to arrive in FRA and check in for my CO flight. I booked these as two seperate round-trips, since the cost was only $1,030 round-trip doing it this way, versus Expedia and Travelocity quotes of $1,800+ for MKE-JNB. Question: When I return to FRA, I am planning to pick up my bags, since they will need to be checked in for the MKE-FRA return flight. Do I have to venture through customs on the way back? Or would LH be kind enough to check them through for me? Also, any advice if my flight from JNB to FRA is delayed by more than a couple hours? There is another LH flight that leaves 10 minutes earlier (SAA Codeshare), but I have no idea what kind of load factor this route has. As of right now, I have scheduled the following:

MAY 19
MKE - EWR CO 3768 13:30 - 16:40
EWR - FRA CO 50 19:45 - 09:30 + 1D
MAY 20
FRA - JNB LH 572 22:00 - 08:10 + 1D

MAY 28
JNB - FRA LH 573 19:25 - 05:40 + 1D
MAY 29
FRA - EWR CO 51 11:30 - 14:00
EWR - MKE CO 4105 17:50 - 19:20

Thanks for the assistance.

MAY 28
JNB - FRA LH 573 19:25 - 05:40 + 1D
MAY 29 FRA - EWR CO 51 11:30 - 14:00

no problem to check your luggage through from JNB to EWR (LH/CO)