LM KNX IP and routing

[domotiqa]

Hello, I have a little problem on an existing project I need to care of.
It was an existing building, that I m in charge now, and the customer don't want to add more device yet...

Here is the topology

   


The Main LM 10.1.12.130 can see all device of all building. I can control GA on visualisation and I have feedback (so the multicast looks like it's working).

1/ On the LAN I can see all IP and I can KNX IP program knx devices from 10.1.12.130 LSS100200 of the 1.0.x and 1.2.x without issue.
2/ I can KNX IP program knx devices from 10.1.12.131 LSS100100 of the 3.1.x without issue.
2/ I can KNX IP program knx devices from 10.1.12.132 IP ROUTER of the 2.3.x without issue.

The problem is when triyng to program from Main LSS100200 10.1.12.130, I can't program the other line 3.1.x and 2.3.x, which when remote program is a problem.

The existing topology is not the best, I hope you have a trick which can avoid the customer to buy more coupler/power supply, change all knx device adress to have correct topology (I mean especially no device on 1.0 only LSS100200 and power supply, then add a line 1.1.x to put all existing 1.0.x device on it).

Any help appreciate