This example is written around a second DTM30, but the principles apply however many boards there are.
The DTM30 recognises a set of 25 DCC addresses which, when set to THROWN or CLOSED, trigger one of its local routes (see manual section 5.2.4). This is the “DCC address to activate routes” in LocoAnalyse. The first 24 of these locations trigger routes. The 25th address triggers the “initialise” feature. So if you set “DCC address to activate routes” on the second DTM30 to 901, then setting DCC address 925 to closed or thrown will initialise all the points on that board.
Now add a new point cell on the first DTM30, with an address of 925. Set it to initialise to THROWN. Now, when the initialise button is pressed on the 1st DTM30, the second one will be made to initialise as well.