Help explain the TREK1000 demo code

I want someone can support me and explain the demo code as follow
1、In my application,I need add the forth anchor used as ranging anchor to anchor;
2、In function of demo code TREK1000
path:->instancce_common.c->void instance_set_replydelay(int delayus)
I found some arrays like “inst->anc1RespTx2FinalRxDelay_sy” and “inst->anc2RespTx2FinalRxDelay_sy”,if I want add the fourth anchor used as ranging anchor to anchor,is it necessary add the other array like “inst->anc3RespTx2FinalRxDelay_sy”?
3、could you confirm If correct as follow for anchor to anchor ranging
3.1:step1:A0 send Poll ,A1,A2 will send response msg ,and how can I do if I want the A3 participate the ranging anchor to anchor
3.1:step2:A1 send Poll,A2 will send response msg,in here how can I let A3 participate anchor to anchor ranging

look forward to you answer ,thank you very much

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