My house is two stories. 15/45A meter with 30sqmm mains. My main panel is 63A with about 12 circuit breakers.

Now the problem is I think my relatives will move in with me temporarily and we need extra amps and wiring for an extra a/c or two. Possibly more refrigerators and t.v.s So I think I have to get a 30a/100a meter.

My question is should I add a second sub panel for the second floor? The main panel already has way too many wires running to it and most of the long wires are from the second floor. I probably would run a 30a sub panel just for the upstairs lights and plugs. Most of the main units like a/c and water heaters would still come from the main panel. Thinking about 10mm sqmm sub mains.

I think I will just connect the ground from the main panel instead of adding another rod.

So is addinga sub panel a good idea or just leave it and jump the wires into the main panels. Like connecting more than 1 circuit to the breakers to free up some breakers?

First, before doing anything else, you should do a maximum demand estimation based on the current load and the new additions you are planning for. That will determine your total requirement and whether you need to fit a new and larger main circuit breaker and apply for a new meter from the electrical authority. Secondly, check with the authority in your area whether your transformer would permit a 30/100 meter.

Note, you should only have one main circuit breaker.

There are a couple of good threads about maximum demand estimation here on this forum and some of the gurus are likely to come to your help as you go along.

Just to comment... Why do you say you have "way too many wires" running into your unit? If all slots are full, you should have 24 single wires coming in (not counting any grounds and ring circuits). If you have more than that, you definitely need a MD and a rethink.

But, I wonder WHY you want to put in A/C for the relatives. Or, maybe they not Thai relatives? Just rhetorical, nevermind.

My load center (30/100) incoming.

You can buy 6 8 10 12 hole breaker boxes. Easy to upgrade. About 1200 baht at an electrical supply store. Schneider Square D.