Hello
Follow the previous blog (Automatic Freight Unit Planning - SAP Community), I will explain a standard way to make automatic planning for a Freight Unit with Multimodal transport mode.
In a scenario you can have multimodal transport mode:
A to B = Road
B to C = SEA
C to D= Rail
D to E = Road
In this scenario will take an example of a FCL using default route to determine the stages in the Freight Unit, for the planning is 1 FU into 1 FO/FB, using this functionality the relationship is 1:1.
In this case you need to create a Default route with the sequence:

FU with Default Route.

In the FUBR as this case is Full Container Load I insert the default Equipment type, allow split of FU and apply default route.

In the equipment you define here be aware that in case you use Container you must need allow to use each according your transportation modes.

If you do not make this step FU will not be create!.
Define the default documents in the Planning profile:

In case you want to use different criteria to use other document types use the condition in the previous Planning Profile.
For this BRF+ Condition considers the Oss Note 2563666 - How to Determine FO Type for FU Types through Condition to use DAD profile /SCMTMS/CAPA_TO_FU.
With this step you should be able to do the Automatic planning for the Freight Unit in multimodal.

Thanks all 😊.
Rogerio Lima.