Thanks, this should be the trick
https://developer.bitcoin.org/reference/rpc/addnode.html

Ok then you could try "bitcoin-cli addnode" commads for the new node and add the old one local. 

relc

I know and I did that manual copy many times in the past. But I do not want that.

I just want a new node to be like a "child" to the old ones and instead of going out in internet to use local nodes. That's all.

So no interruption of existing nodes, just a smooth local sync. Once is done, to switch back to "normal" sync.

I know it is a bitcoin-cli command but can't find right now.

I remember I did something like that long time ago with Bitcoin Core/QT app, pointing to another node in LAN and grab the blocks from that local IP.

bitcoin

Question: Is there a way to sync a new BTC node from a trusted LAN node?

DarthCoin

I know and I did that manual copy many times in the past. But I do not want that.
I just want a new node to be like a "child" to the old ones and instead of going out in internet to use local nodes. That's all.
So no interruption of existing nodes, just a smooth local sync. Once is done, to switch back to "normal" sync.
I know it is a bitcoin-cli command but can't find right now.
I remember I did something like that long time ago with Bitcoin Core/QT app, pointing to another node in LAN and grab the blocks from that local IP.