3. The meaning 'central' for the idea of a delta seems to have been used also in our basic picture of the Andromeda constellation, where δ (Delta) - cfr at Alamak - marks the cross between the line from π to ε and the line from α (Sirrah) to β (Mirach):

Gb7-5 Gb7-6 (417) Gb7-7
   Delta (417.4) Schedir (417.6), Deneb Kaitos (418.4)

... Counting from day number 365¼ there are 52 days (13 weeks) to Delta. This seems significant because Gb7-6 (where 7 * 6 = 42) is a Monday and the glyph type is raaraa (no Sun) ...

Where a river runs down to its end ('mouth') it divides into numerous small streams in a marshy area where it no longer is possible to discern between terra firma and the sea - it is the delta of the river.

The river Nile divides the (female) land into 2 'legs' and its fertile delta surely is where it should be. Though its triangular form is upside down compared to Δ - it is more like a cup than a cap.

When Andromeda has her delta star at her back it could mean the 'delta land' is in the past. The location of Sirrah is at the beginning of the summer half of the year. The new 'year' has just been born.

Facts about π Andromedae and ε Andromedae according to Wikipedia - I cannot find them in Allen - show that they rise so close to Delta that we should not try to separate them:

π 00h 36m 52.84s 00h 36.881m 416.8
ε 00h 38m 33.50s 00h 38.558m 417.2
Delta 00h 39m 19.60s 00h 39.327m 417.4
Gb7-6 (417)
 π Andromeae (416.8), ε Andromedae (417.2), Delta (417.4)

Also in Polynesia they divide land into uta (upland) and tai (the coast), in contrast to the deep sea (moana). The 'living land' (henua ora) could be the coastal wetland area, between the high and dry area on one hand and the purely watery domain on the other:

henua ora