Whatever you do as a parent there is no guarantee that your children will get on together.
Just because people are related that does not mean that they will like each other.
However, you should avoid encouraging sibling rivalry and treat all your children as individuals.
Never ever hold up the achievement of one to belittle the other.
It will only create tension and lead to unnecessary jealousies. Try not to show favoritism and if you treat your offspring with respect, they will do the same to siblings.
Even at a young age, a child will feel a sense of injustice and know when they are treated unfairly. Brothers and sisters need to get to know each other and will develop their own relationship.
Stand back and let that happen. Try and find time for each child individually so that they can know that they have an equal slice of your day or week
There is always going to be the occasional argument or fight between brothers and sisters, this is only natural, however well they get on together.
If possible let them work it about without intervention although if it gets too heated it might be best to step in.
If there are regular disagreements it might be worth examining the cause, often there will be a simple solution that can clean the air and let the relationship move on. Be fair and let each side state their case; explain about compromise because often this is what is required.