For whatever the reason, you ended up with several children as your responsibility. If you adopted a big batch of kids, had multiple sets of multiple children or just married to someone with a load of children from his/hers previous marriage doesn't matter right now. You just need to get them to like you, obey you and, most important, become proper behaved little people. This article is directed at those parenting multiple children or handling them for a fairly long time period (say, a couple of months)
If you need help dealing with being in charge of children for a limited period of time, like in a party, see How to Handle Multiple Children
Implement a safe word as early on as possible. This safe word will act as an extreme command, when you can't handle all the children and the house is a mess. It's not unusual to be some sort of code word (e.g., Tapitapou, Bipibopi or other silly nonsense) a word from your actual language that conveys the adequate meaning (e.g., quiet, stop, silence time, timeout, etc.) or a sound that resembles what you need them to do, which works best with younger children (such as "shush"). Teach them that whenever they hear this word, they are all to gather around you, sit down and shut up. (or whatever works for you) Then you'll be able to pass on instructions to the children or an important message.
Know all the names if you don't already. Nickname differently children with the same forename and keep a list of all of them with you if you don't know it by heart. It may help (if you're any good at drawing) to make small sketches of the distinctive features of each child next to their name. If there are enough children to make this worthwhile and if all the children are at least five years old, you could implement a "self-counting" system in which you assign a number to each child, in order. When you yell "self count" you should hear child number one say "ONE", child number two say "TWO" and so on. If there isn't a perfect sequence, someone is missing.
If you find yourself living with identical twins and have trouble telling them apart, look at them thoroughly. Surely there is a distinctive feature like a mole or their voice. If all fails, get them to cut their hair differently
Establish a routine firm enough for the children to know what they're counting on. Set the raising time the same for all children and bedtime according to age, meals always at the same time and place and a basic structure for the day. Service scale: It can be a blessing if you know how to do it right. Sit down with all of the children in a circle when you decide to establish it and tell them you are passing on to them a big responsibility. Together decide on which house chores should be handled by which children and when. You can, for instance decide that 14-year-old Sally is mature enough to do the laundry the first Sunday of every month, while 10-year-old Tony would be a better help if in charge of feeding the house pet. Instill from the very start a tidy environment or soon you'll be living in a pigsty. Decide on how tough you want to be on them. You can demand that the common areas be free of personal objects but the cleaning of their rooms is on their judgement or you can be as tough as demanding their rooms impeccable and even make periodical inspections. For the sake of organization, assign each child a colour (preferably their favorite) and make sure that each personal item that may be there a lot of (toothbrushes, combs, bath towels) is of the proper colour. If Sally's toothbrush is lime green, her bath towel, comb or even manicure items should be at least marked lime green. A good way to mark things is to make a small dot with nail polish. If the color desired is unavailable, make it white and paint over with a marker or paint. Make sure each child has a specific place to be in common areas and a least a portion of a room only for him/her. If Tony knows his place at the dining table, he won't sit in Emma's place next to mom, which could make little 3-year-old Emma cry. Many people only think of the dining table, but the couch is also important as only one can get the best seat right in front of the screen. Limit this kind of fights with assigned seats.