Sorry all , I didnt got a right answer while the problem is
Miner 1 worker A make 1.000.000 best share
Miner 2 worker A make 3.000.000 best share
Miner 3 worker A make 20.000.000 best share
In solo pool what is the right best share for worker A (Real best share ) ?
and if Miner 3 down did the pool still save his best share ?
Who cares? The shares are completely irrelevant until one of them exceeds the target network difficulty. To answer your question, yes, the pool does save your best share. For example, we lost power at my house a few nights ago. My rPi didn't automatically restart cgminer (yeah, I should probably fix that), so my 5 U2s are not currently mining. Yet, here is what is shown from ckpool:
{"hashrate1m": "0", "hashrate5m": "0", "hashrate1hr": "0", "hashrate1d": "0", "hashrate7d": "0", "lastupdate": 1429712208, "workers": 0, "bestshare": 5211017.239969668}