When commands are grouped with parentheses, the stdin for the next command is collected from all the grouped commands, eg
user@system:~$ (echo 1; echo 2; echo -e '3n4') | tac
4
3
2
1
vs
user@system:~$ echo 1; echo 2; echo -e '3n4' | tac
1
2
4
3
Is there a way to do the inverse of this, where the stdout of one command goes to all the grouped commands, eg
user@system:~$ echo -e '1n2n3n4n5' | (tail -n2; head -n2)
4
5
1
2
One specific useful example for this could be a table with a header:
user@system:~$ cat datatable.md | (head -n2; sed '1,2d' | sort)