I dont think that Abba is quite the same as daddy
which is familiar but also faintly silly isnt it?
Abhishiktananda(a Catholic priest and wise man) said
that the best prayer he knew was OM-ABBA expressing the
ground of Being and the intimate fatherhood of God.
But God has many names and each name is a way of access
and there can be and must be finally perhaps one particular
name for each person to discover as well as those which
are for all.
or so it seems to me...
+Seraphim.