Dhatri is a name made out of a very common verb. The root dha means to put, place, set or found, and it is one of the busiest roots in Sanskrit: it gives dharma, that which holds things up, and it appears in dozens of ordinary compounds. Dhatri is its agent noun, the one who places, and the tradition uses the word in three different ways at once, which is why the figure is hard to pin down.
It is used as an epithet. A hymn can say that some other god established the sun in heaven and call him the establisher without meaning a separate being. It is used as a divine name in the later parts of the Rigveda, where Dhatri appears among the gods invoked for offspring, for long life and for the securing of what one has. And it is used in the classical language as one of the standard words for the creator, so that Dhatri and Vidhatri, the placer and the disposer, appear as a pair in Puranic Sanskrit for the ordering power behind events.
That range is not confusion. It reflects a genuine feature of the later Vedic period, in which abstract functional names were being promoted into gods: Prajapati, the lord of creatures, and Vishvakarman, the all-maker, come up the same way and at roughly the same time. Dhatri belongs to that stratum rather than to the oldest one, which is why he has hymns but no myths.