Hi,
Can one say:
1-Your present brother...or:
2-Your brother here present...instead of:
You brother who is now present here...All of the above sound unnatural. Here are a few more natural suggestions.
If you know the person only has one brother, simply say 'Your brother'.
Otherwise ....
If the person's brother is part of the conversation,
still say 'Your brother' and glance at the brother to show you mean him.
If the person's brother is not part of the converation, but is somewhere else in the crowded room, you might say things like
'. . . your brother who's here . . . '.
'I just talked to your brother'.
'I saw your brother a moment ago'.
As you can see, much depends on the situation in which you are speaking.
Best wishes, Clive