In case it will help anyone, found a solution.
Its pretty simple:
Declare Vector Array as user input,
set it before Activate() method
UNiagaraDataInterfaceArrayFunctionLibrary::SetNiagaraArrayVector(NiagaraComponent, FName("StartLocations"), Positions);
NiagaraComponent->Activate(true);
And produce by “Spawn Burst” number of particles = user input vector array count
in “particle spawn” extract each particle input by its ExecIndex (ExecIndex = index of spawned particle by Spawn Burst)