Saving methadone questions

How do yall store your extra clear unflavored methadone when you have to return your bottles? Do you put them in a bunch of small bottles to keep the doses separate or all in one big bottle and just measure out doses later? If I do the later whats the the mg of methadone per ml? I cut my dose drastically and am going to have alot saved up quick so I dont want to end up with a big bottle full that I cant correctly dose.