Are all maternal uncles and aunts considered siblings, and thus is it permissible to unveil in front of their children, or not?

Your grandmother suckling your older brother makes him her son through suckling. Your mother suckling your youngest aunt makes her your sister through suckling. Your second aunt suckling your siblings makes them her children through suckling. Your older brother is a mahram (definition) to all your maternal uncles' and maternal aunts' daughters. Your siblings who were suckled by your aunt are siblings through suckling to her daughters. As for you, there is no mahram relationship between you and the children of your maternal uncles or maternal aunts, except for the children of the aunt whom your mother suckled, for they are the children of your sister through suckling.