Restrict Planning of Subsequent stage of FU before preceding stage is planned

Hello Experts,

We are a Shipper company with TM 9.1:

We have a multi leg scenario leading to FU split into stages using Default Route:

Stage 10: A----B

Stage 20: B----C

Stage 30: C----D

We want system to plan stage 20 of the FU only after stage 10 is planned

Likewise, stage 30 should be restricted for planning before stage 20

Please suggest how to handle it in SAP TM

Thanks and Best Regards,

Vikram Bhardwaj