My pre-merge spec. complete with colorful laminates (Sorry, only the oldsters are gonna remember that reference)...

We know the OLD tribal distribution of the merged tribe.

F12 Merge (original tribal breakdown)
Tandang (6)	Matsing (4)	Kalabaw (2)
Michael	Denise	Jonathan
Lisa	Malcolm	Dana
Abi-Maria	Russell	Katie
Pete	Angie	Carter
Artis	Roxanne	Jeff
RC	Zane	Dawson

We also know the F7.
(4 will be from Tandang, 2 will be from Matsing and 1 will be from Kalabaw.)

F7 tribal perspective
Tandang (4)	Matsing (2)	Kalabaw (1)
Michael	Denise	Jonathan
Lisa	Malcolm	Dana
Abi-Maria	Russell	Katie
Pete	Angie	Carter
Artis	Roxanne	Jeff
RC	Zane	Dawson

As previously stated, this leaves the Tandang 6 completely intact at Merge with 4 Matsing and 2 Kalabaw also there.
On Matsing, Denise and Malcolm for sure make it, so 2 of Russell, Angie, Roxy and Zane also make merge.
On Kalabaw, Jonathan is the only guarantee for merge, so only 1 of Dana, Carter, Dawson, Jeff and Katie make merge.
Therefore, Matsing loses 2 members before merge, while Kalabaw loses 4 members.

So, now we can kind of split the slate up a bit more...
F3: Denise ~ Lisa ~ Michael
F7 - F3: Pete ~ Jonathan ~ Abi ~ Malcolm
F12 - F8: Artis ~ RC ~ Russell* ~ Angie* ~ Dana* or Katie* (*: Russell because he's a returnee and Angie and Dana because they were the first non-celebs to be spoiled, which is why I think Katie might also be important.)
F18 - F13: 4 Kalabaw / 2 Matsing

Considering my earlier postulations regarding a tribal absorption... in order for the "Alliance of 6" to be consisting of Michael, Lisa, Abi and Pete (Tandang) and Malcolm and Denise (Matsing), I had thought it would mean that Matsing or Tandang will have to be the tribe that is absorbed. However, you'll see as I did, that the absorbed tribe will have to be Kalabaw. Meaning also that the alliance of 6 does not get proposed until AFTER the merge.

Now, take into consideration that the absorption episode (at least last time) was after 4 people had been booted...
Meaning also that after absorption the tribes should be split 7 to 7.
Also, going through the various options with early boots and tribal absorptions; The 'occom's razor' version has Kalabaw as the absorbed tribe, 3 players go to Matsing and 1 player goes to Tandang.

Kalabaw Absorption
Tandang	Matsing
Michael	Denise
Lisa	Malcolm
Abi-Maria	Russell
Pete	Angie
Artis	Carter
RC	Dana
Jonathan	Katie

A single Kalabaw is residing at Tandang, while a minority of 3 Kalabaw now resides at Matsing. Ripe for the 2 Kalabaw boots before Merge.
(What would be exciting is to have Jonathan be the single Kalabaw at Tandang, but they continue to be challenge whores and the next two boots come from Matsing.)

F18 - F15: First 4 boots = (2 Matsing / 2 Kalabaw): Zane & Roxanne / Jeff & Dawson
F14 - F13: Pre-Merge Boots = (2 OLD Kalabaw): Dana or Katie & Carter
Merge @ F12: (6 Tandang / 4 Matsing / 2 Kalabaw)
Tandang: Michael ~ Lisa ~ Abi ~ Pete ~ RC ~ Artis
Matsing: Denise ~ Malcolm ~ Russell ~ Angie
Kalabaw: Jonathan ~ Dana or Katie

In closing, I suspect we will see Zane and Roxanne (from Matsing) and Jeff and Dawson (from Kalabaw) as the first 4 boots.
(It could be that Jeff and Carter are switched, but I have a feeling Jeff is completely out of his element here and will instantly be a tribal-unity crasher. Despite his physical ability.)

From there Kalabaw will be absorbed and split amongst Tandang and Matsing. Leaving tribes 7 to 7 OR (6+1) to (4+3).
Where Matsing will most likely lose the next two challenges and boot 2 OLD Kalabaw as a result of Tribal Councils.

Post Merge we will have the creation of the "Alliance of 6". These 6, plus Jonathan ALL make F7.
Leaving the next 5 boots as 2 Tandang (Artis and RC), 2 Matsing (Russell and Angie) and 1 Kalabaw (either Dana/Katie or Carter).

I'd even go further to speculate that Mitsang will lose IC 1, Kalabaw will lose IC 2 and IC 3, Matsing will lose IC 4, Kalabaw is absorbed and Matsing loses both IC 5 and IC 6 (booting OLD Kalabaw).
Post Merge is a little convoluted, but I gather that with the NEW "Alliance of 6", both Artis and RC will be early jurors. (Probably dependent on their early inter-tribal dynamics, someone is always on the outside of an alliance.) As well, Russell and Dana/Katie will also be early jurors. I imagine that Angie will last the longest and be cut just before F7 because of her likeability factor.

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My pre-season Boot-List:
F18: Zane
F17: Dawson
F16: Jeff
F15: Roxanne
F14: Carter
F13: Dana/Katie
F12: Artis
F11: Russell
F10: RC
F9: Dana/Katie
F8: Angie
F7: Pete
F6: Jonathan
F5: Abi
F4: Malcolm
F3: Denise ~ Lisa ~ Michael