ALVES
Portuguese: the usual Portuguese form of Alvares
> Portuguese: from a patronymic form of the personal name Álvaro (see
Alvaro)
> Spanish (Álvaro) and Portuguese: from the personal name Álvaro, which is of Germanic (Visigothic) origin, although the exact etymology is not clear.
GRELL
1. nickname for an irritable, irascible person, from Middle High
German, Middle Low
German grellen ‘to be angry’.
2. habitational name from a place named Grelle.
This is from: Dictionary of American Family Names, Oxford University Press
The DUDEN, Familiennamen has:
ALVES:
Lower
German patronym of
Alf
GRELL:
1. from Middle High
German "grel" (rough, angry)
2. from Middle High
German "grelle" (stick, spear) for someone making or using a weapon of the kind
So take your pick!