Help me Optimize my Dual Summoner Build

[Ramaloke]

Ok, so this build is using a Deep Imaskari with the otherworldly feat, and using the Ritual of Alignment to get the Evil Subtype. Making the character a Outsider (Evil).

This qualifies me for Fiend of Possession, which Ive managed to nab at level 5, so that I can possess my cohort. The idea is to get the benefit of the Malconvoker Class, and the Fiendbinder class, AND the Nar Demonbinder class. If you can think of a better way to arrange this all, it would be really keen.
[spoiler=Main Character Class Progression]

Code:

Class:
Lvl01 Conjurer 01
Lvl02 Conjurer 02
Lvl03 Conjurer 03
Lvl04 Master Specialist 01
Lvl05 Fiend of Possession 01
Lvl06 Fiend of Possession 02
Lvl07 Fiend of Possession 03
Lvl08 Fiend of Possession 04
Lvl09 Fiend of Possession 05
Lvl10 Fiend of Possession 06
Lvl11 Master Specialist 02
Lvl12 Master Specialist 03
Lvl13 Master Specialist 04
Lvl14 Nar Demonbinder 01
Lvl15 Nar Demonbinder 02
Lvl16 Nar Demonbinder 03
Lvl17 Nar Demonbinder 04
Lvl18 Nar Demonbinder 05
Lvl19 Nar Demonbinder 06
Lvl20 Nar Demonbinder 07

[/spoiler]
[spoiler=Cohort Class Progression]

Code:

Cohort Class:
Lvl01 Wizard 01
Lvl02 Wizard 02
Lvl03 Wizard 03
Lvl04 Wizard 04
Lvl05 Wizard 05
Lvl06 Malconvoker 01
Lvl07 Malconvoker 02
Lvl08 Malconvoker 03
Lvl09 Malconvoker 04
Lvl10 Malconvoker 05
Lvl11 Malconvoker 06
Lvl12 Malconvoker 09
Lvl13 Fiendbinder 01
Lvl14 Fiendbinder 02
Lvl15 Fiendbinder 03
Lvl16 Fiendbinder 04
Lvl17 Fiendbinder 05
Lvl18 Fiendbinder 06

[/spoiler]

The thing that sucks is I cant figure out how to get 9th level spells in here too, just 8th level. Feats shouldn't be a problem, as I can grab them with either the cohort or the main character.

[PhaedrusXY]

This qualifies me for Fiend of Possession, which Ive managed to nab at level 5, so that I can possess my cohort. The idea is to get the benefit of the Malconvoker Class, and the Fiendbinder class, AND the Nar Demonbinder class. If you can think of a better way to arrange this all, it would be really keen.

Thrallherd + Fusion. This solves a lot of these kinds of problems.

The fused being has your current hit points plus the other creature’s current hit points. The fused being knows all the powers you and the other creature know, has the sum of your and the other creature’s power points, and knows or has prepared any spells you or the other creature possesses (if any). Likewise, all feats, racial abilities, and class features are pooled (if both creatures have the same ability, the fused being gains it only once). For each of the six ability scores, the fused being’s score is the higher of yours and the other creature’s, and the fused being also has the higher Hit Dice or manifester level—this effectively means the fused being uses the better saving throws, attack bonus, and skill modifiers of either member, and it manifests powers at the higher of the manifester levels that you or the other creature possessed before becoming fused.

Take characters with the PrCs and feats that you want as Thralls, and then Fuse with both of them.

[Ramaloke]

So, I discovered something interesting, a Spellstitched Necropolitan can qualify for Malconvoker at Level 1, like this
[spoiler=SpellStitched Necropolitan Demon Summoner]
Referencing Complete Arcane page 72, under Specific Spell Requirements, we learn that Spell Like abilities can qualify you Prestige Classes and Feats that have the wording of "Ability to cast XXXX." So with 16 wisdom you get two 3rd level spell likes per day, which you make Summon Monster III. There, you qualify, the only problem is the following:

• The Ritual of Crucimigration (Libris Mortis page 115) costs 3,000 gold.
• Spell Stitching (Complete Arcane page 161) costs 1,000g, and 500 XP x Wisdom, bringing the cost of spell stitching to 41,000gp (16x500x5+1000).
• You should only have about 2,700gp at level 3.

So to do this you would either have to find some adamantine doors to sell, or start off at level 10 and spend most of your 49,000gp on it and be poor for a long time. You have to be a Sorcerer, and a race that has an extra feat so you can get Bluff 4, Knowledge (The Planes) 4, Spell Focus (Conjuration), and Augment Summoning. Malconvoker requires you to be non evil, which is lucky since Necropolitan doesn't force you to be evil (the example necropolitan is neutral).

Code:

Spellstitched Necropolitan
Lvl01 Sorcerer 01
Lvl02 Malconvoker 01
Lvl03 Malconvoker 02
Lvl04 Malconvoker 03
Lvl05 Malconvoker 04
Lvl06 Malconvoker 05
Lvl07 Malconvoker 06
Lvl08 Malconvoker 07
Lvl09 Malconvoker 08
Lvl10 Malconvoker 09
Lvl11 Fiendbinder 01
Lvl12 Fiendbinder 02
Lvl13 Fiendbinder 03
Lvl14 Fiendbinder 04
Lvl15 Fiendbinder 05
Lvl16 Fiendbinder 06
Lvl17 Fiendbinder 07
Lvl18 Fiendbinder 08
Lvl19 Fiendbinder 09
Lvl20 Fiendbinder 10

[/spoiler]

[Ivory Knight]

Could you replace your Cohort with the Necropolitan Sorcerer 1, spellstitch him yourself and then get him up to Level(your Main Charakter -2)?

Would save some Gold too, but cost 8000XP. If you take Leadership at Level 9 and put 2/3 of your Wealth into your Cohort, it should work.

Unfortunatly, I don't know, if it is possible, to take a Lowlevel-Cohort and how long it would take him, to get up to your Level -2.
The Wording of Leadership would get him(Level 1) 75XP per CR9 Encounter, so I doubt you want to wait that long