[Lingtyp] Please help me label two Dalkalaen (Oceanic) TAM markers

[Cat Butz]

Dear Lingtyp community,

I'm trying to understand the function and relationship of two morphemes 
in Dalkalaen (Oceanic). I'm not sure they're prefixes, but for now, 
let's assume they are. They both occupy the same slot in the prefixal 
template of verbs, namely the outermost one.

1.: ga-
As far as I can tell, this prefix serves four functions:
a) specific temporal co-/subordination, e.g. GA-go "when they went (to 
place x, event y happened)"
b) general temporal/conditional co-/subordination, e.g. GA-chirp "when 
[a kingfisher] chirps (under circumstances x, then that means y)"
c) final/purposive subordination, e.g. GA-make "(x got ready) to make 
(food item y)", ga-GO "(x got up) to go (to the restroom)"
d) a kind of general complementation, e.g. we want GA-x "we want that x 
happens"

2.: sa-
This one never occurs on its own, but always in combination with
a) the potential marker (which refers to future possibilities, 
prospectives, hortatives), in which case the combo seems to refer to an 
undesirable prospective, e.g. SA-POT-eat "this fire could/will consume 
me [if I don't get out of here]". This combo is pretty rare.
b) the negative potential marker, which in fact can't occur without sa-. 
This combo refers to warnings and prohibitives, e.g. SA-NEG.POT-fall 
"(watch out so you) don't fall!", but also to more generally negated 
future possibilities, e.g. SA-NEG.POT-hurt "we're not going to / don't 
want to hurt you".

Ga- also often occurs with other TMA markers, including the potential 
marker, but I haven't been able to identify any kind of transparent 
pattern as to what exactly those markers contribute in those contexts; 
they seem to be kind of optional and interchangeable.

So my question is basically: How would you label these two markers?

Please send ANY kind of idea, literature recommendation etc. etc. etc. 
my way. Thank you, and I hope you have a nice week.

Warmest,
-- 
Cat Butz (she)
HHU Düsseldorf
General Linguistics