You said: The last possible solution recognizes that the "Passover" was a figure of speech that included all the week of the Feast of Unleavened Bread.
Maybe last for some but according to scripture: Eze 45:21 In the first month, in the fourteenth day of the month, ye shall have the passover, a feast of seven days; unleavened bread shall be eaten. Pretty good support for something that is in last place?
Because that quote from Kenneth Doig's book says that it is the last possible solution, it doesn't mean that it is the least likely or least significant. I personally think that it is the most likely due to the length of the Festival of Unleavened Bread.
Indeed, I fully agree with your comments about the lamb being eaten ONLY on the first day...
When you sacrifice an animal on the altar, don't offer bread made with yeast. And don't save any part of the Passover meal for the next day.
[Exodus 34:25 CEV]
This passage obviously alludes to the lamb and to the Seder.
The following passage confirms that it was the Passover Meal / Seder that Jesus was eating.
He said to them, "I have wanted so much to eat this Passover meal with you before I suffer!” Luke 22:15
The bread was significant, in that it was ordained by God not to have any yeast in. Yeast represents sin, this new type of bread was to be "sin free"
There does seem to be much confusion between Jews about how long the festival lasts some say 8 days, some say 7. I have not come across anything that jumps out at me regarding the Sabbath. I do however have a good book called "Jewish Family Celebrations" by Arlene Rossen Cardozo, which explains a lot about the merging of two festivals - The Pesah meal and the Festival of Unleavened Bread.
She says that the Pesah meal became the occaision for the Passover Seder (historic, emotional and spiritual aspects of the Exodus) and the week long Festival of Unleavened Bread became symbolic of the practical aspects of the Exodus (fleeing before the bread could rise etc).
If you can't track down a copy, I will scan the relevant pages for you. It is a bit beyond me as it has much to do with different groups of Jews thinking different things.
To sum it up. I cannot agree with the Witness position that the Last Supper was an event separate from the Passover Seder. They seem to think that Judas was present at one and not the other. This linking of the Passover to the "Last Supper" makes a lot fall into place
This sums up my view... " As the Jews practiced these laws and rituals, they would learn through their physical senses [the] spiritual truths concerning their relationship with God." Jesus in the Feasts of Israel”, Richard Booker, Bridge Publishing - 1987
AO