A Spool of Blue Thread question

The obvious answer for the title's meaning is that it is a reference to the spool of blue thread that falls out when Denny opens a closet. It is the exact shade of thread that he needed to make some repairs to his dad's shirt for the funeral. Denny thinks his mom's way of helping him find it.

I think a more figurative meaning of the title is that after the bad event that happens half way through, the perspective of the book changes and we are able to see to interconnected the mom is in everyone's stories and how many secrets she is hiding.

Yes, the title is not only alluded to when the spool of blue thread falls out of the linen closet. Denny needs to repair the dashiki that Abby had made for Red to wear at their wedding, because he wants to wear it to her funeral (196-7). I think that the ribbon of blue paint Junior finds running down the flagstone walk when he takes his family to the house is another (or the same?) thread connecting Abby to Linnie. Both Junior and Red are single-minded, focused men who are involuntarily tied to their imaginative, nurturing, resourceful wives.
Note that Denny (the unmarried son) is the one who offers to mend the dashiki and it is he who interprets the sign that Abby has sent him (379-80) for Nora, as she is driving him to the train station. He trusts Nora with this spiritual insight, helping him feel the connection to his mother -- but he tells no one else. I was very moved by that passage. There is so much more to Denny than anyone except Nora understands.
What did you think of Nora? Do you know anyone like her? There is this harmony between Nora and the world. She knows something the others don't. She is like an old soul who is at home in the world, whereas the others have to try to make a home there.

The title of the book is interesting and one with many meanings
1. The moment the blue thread dropped into Denny hands and he feels a sense of otherness, that can not be explain by reason but is more faith or religious. These moments of otherness are see throughout the book. The unexplained. The life that happens in the silence. The oddness and strangeness of life. Such as when Abby is hit by the car and knows it the end. Or the man playing music in his car that reminds the family of Denny.
2. The blue thread represents the family line and could be associated with blue blooded-another family lineage. Also it being a thread and a line, a connection going back and into the future. Which this book is all about the history and possible future of the Whitshank family.
3. The blue thread is also a connection to two huge events in the book. Abby's marriage and funeral. Which again this book is all about the about big and small moments in life. Relationships starting,, buying house, family vacations and traditions.
4. I like to think the blue thread also indicates the rebellion and socially redefining nature of many of the characters in the book. First used in Red wedding suit in the rebelious 60s-a far cry from the con formative and social upward family we see him with in the 50s-Junior must have hated it! Also the fact Red wears it at his wife's funeral-despite his children thinking he should wear a dark traditional mourning suit. Again he wears it to represent his wife and there love
5. The rebellious and strong connection of blues can also be seen between Linne and Abbey with Linnie anger over the blue paint. But there are also other strong rebellious people in this family. Junior who has an affair with a 13 year old-leaves home and starts his own successful business is strong and unconventional-given his background. And Denny defies normality by his choice (or non choice) in career, home, wife and father responsibilities.

Nancy wrote: "I am wondering if readers thought of meanings that could be hidden (or obvious) in the title of the book. Does anyone have any thoughts?"

I was thinking that thread is a very ordinary thing. It’s what is made with the thread that becomes extraordinary. If relationships are seen as thread, then this is a beautiful metaphor and clever title.

You could also think of thread as keeping something together. Stereotypically, the mom keeps the family together and this is played out in the story as well.