Here is my diagram for the genealogy (verses 1-16):
And here is my 'chiastic' arrangement (inverted parallel structure) for the birth report scene (verses 18-25):
The writer has positioned the scripture quoation into central position (rather than waiting until the end of the scene) so that it becomes central. Here's a brief guide to the segmentation:
In both A and A' Joseph’s marriage situation is given whereby the writer asserts in both that Joseph has not yet had sex with Mary either in the first stage of marriage (‘before they came together’) or in the second stage when (‘he took her as wife’). But with ‘before she gave birth to a son’ the writer finishes the report with ambiguity regarding whether they later began to have sex (this is irrelevant to the writer).
In B is Joseph’s original plan of action which is inverted by following the divine plan in B'.
In C and C' the writer parallels the name that Joseph is to call Jesus (and its significance) with the name that people will call him.The writer uses biblical quotation in the birth report to provide support for the central assertion that Joseph’s discovery of Mary’s pregnancy fulfils scripture (D).
I am still finding fresh discoveries in chapter 1...most recently concerning Joseph's fear of following through with marrying the pregnant Mary...stay tuned...