MailStream Why were zipcodes for FSS mailing pieces not placed in FSS tray but placed in MADC sacks

The FSS mail Pieces are placed in MADC Sack and not the FSS sack because the two FSS sack are full and what is left does not make a full FSS sack; so the additional mail pieces are rolled to the next level. There are no overflow containers in Flats. When placing Flat mail in letter trays the container maximums are based on the Tray size. Since Flat mail in letter trays are only valid when they are placed on pallets. What MSP does for trays that fall off pallets is to change the container type to sack but the content of the container does not change. 

Note: This is not new to MailStream Plus the software handles this type of mailing and works as designed. 

The software attempts to 
Maximize containers per the USPS requirements for Standard Flats 150 pieces or 15 lbs.
USE - ALG PS position 10 [N]  to split the containers evenly the containers should meet USPS min requirements.

Maximize Mail Containers
Maximize containers or split evenly?
[Y] MailStream Plus will maximize all containers and create a less than-full overflow container, if allowed.[DEFAULT]

[N] MailStream Plus will fill all but the last two containers to the maximum value. MailStream Plus will then attempt to fill the next to-last container
to the force amount and use the remainder to create a legally-full last container. If the remainder does not create a legally-full last container
or does not fit in the last container, MailStream Plus will maximize the next-to-last container and create a less-than-full overflow container, if allowed.  
UPDATED:  September 6, 2017