For this part I will simply be taking a few bits of information we do have in the series, and use them to make an albeit headcanon count of their members, but it is the closest thing we realistically have to go on.
For this, I will make a backbone statement and use it as the premise:
"The Zeus and Hera familias combined had at least the same number of powerful upper lever adventurers as the Freya & Loki familias combined."
So… Let's find out how many high level adventurers Freya and Loki have:
Level 7s : 4 (Ottar(might be lvl8 soon), Finn, Gareth, Riveria)
Level 6s : 8 (Allen, Hogni, Hedin, Mia, Ais, Tione, Tiona, Bete)
Level 5s : 6 (Grer, Alfrigg, Dvalinn, Berling, Raul, Anakitty)
Level 4s : 15 (Misc)
So, we could go a few ways here, as the numbers above are as they are currently. We have a known level 9, and level 8 in Zeus & Hera familias, with 2 7s. I will not add Leon into this mix for the express reason he is NOT a member of either familia.
First option: We can just take the four known level 7 & higher members as the level 7 number. This results in a rather hyper over simplistic representation of the familia strength, and is the absolute weakest we could make them.
Level 9s : 1 (Empress(lvl9))
Level 8s : 1 (Maxim(lvl8))
Level 7s : 2 (Alfia(lvl7), Zald(lvl7))
Level 6s : 8 (Misc)
Level 5s : 6 (Misc)
Level 4s : 15 (Misc)
You can probably see the problem with this particular situation right? It just hyper casually ignores the struggles of reaching those higher levels, while also assuming that the other members couldn't do the same, in short the level spread is off, and overly unbalanced to the point it feels worse than Telskyura's issues.
Second option: We treat the familia levels with Ottar as a "level 8" instead to account for the potential he would also level up like many others did from the start of the series.
Level 8s : 1 (Ottar)
Level 7s : 3 (Finn, Gareth, Riveria)
Level 6s : 8 (Allen, Hogni, Hedin, Mia, Ais, Tione, Tiona, Bete)
Level 5s : 6 (Grer, Alfrigg, Dvalinn, Berling, Raul, Anakitty)
Level 4s : 15 (Misc)
Now… Let's make everyone have the same number of individuals starting from their highest, to their lowest.
Level 9s : 1 (Empress(lvl9))
Level 8s : 3 (Maxim(lvl8), 2 miscs)
Level 7s : 8 (Alfia(lvl7), Zald(lvl7), 6 miscs)
Level 6s : 6 (Misc)
Level 5s : 15 (Misc)
Level 4s : Some number likely greater than 10
In this case we show that there is an equal number of individuals all 1 level higher than the current generation. This is probably the most balanced, and fair choice to go with, despite it also having several issues.
Third option: We use the level spread of Freya & Loki from just after the series began.
Level 7s : 1 (Ottar)
Level 6s : 7 (Allen, Hogni, Hedin, Mia, Finn, Gareth, Riveria)
Level 5s : 8 (Grer, Alfrigg, Dvalinn, Berling, Ais, Tione, Tiona, Bete)
Level 4s : 12 (Many…)
Now you're probably seeing where this is going, right?
Level 9s : 1 (Empress(lvl9))
Level 8s : 7 (Maxim(lvl8), 6 miscs)
Level 7s : 8 (Alfia(lvl7), Zald(lvl7), 6 miscs)
Level 6s : 12 (Misc)
This version paints a clear picture of just how mighty they were.
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With the options laid out, allow me to add some extra tidbits… The dungeon begins to more rapidly scale up in difficulty the further down one actually gets. We know that floor 71 was their limit thanks to Alfia & Zald's status sheets. Knowing this, I'm far more inclined to go with option 3 as it provides a far more reasonable explanation to their ability to reach floors that deep, than both other options.
So for the purposes of scaling the OEBD, I will be using the collective strength of Zeus & Hera familias as laid out in option number 3.