Here is a new update from Snapchat. It's called Snapchat Plus.
With this Snapchat Plus, if you upgrade, you can tap and hold on your friend's account name, and then here in the top, you will see this option to pin your friend as number one friend. Then it will appear in the top of your chat and Snapchat.
Your BFF will appear under separate category "Best Friend" in the top of your chats.
That's cool. And you do that with a new SnapChat Plus subscription - $3.99 per month with a 7 day free trial.
At the moment it is only possible to pin one friend - not many. But, it is quite convenient as you don't need to search every time for your friend among other chats.No answer to your question? ASK IN FORUM. Subscribe on YouTube!