I did some research recently on Blood Knights, it led me to a number of images including this:
https://www.reddit.com/r/WarhammerFantasy/comments/nn7wy6/new_blood_knights_ranked_up/
Blood Knights are vey big, but they can be accommodated.
OPTION 1.
As a last resort you can have the unit on numbered bases and always assemble them in a specific order. This gives you the most leeway, and simplest solution. Thus I link it first..
I don't do this, partly because I want to leave the unit free for adding characters or for loss of specific models, such as champion and standard.
OPTION 2.
My favourite technique is to build models alternately forward or back, with the champion and standard bearer being opposed, so they can be adjacent.
When assembling a dryfit a model then glue in a model in the opposed configuration, I keep this model aside and glue in the original model. Then I add new members to the unit forward or back and I dryfit them to each and every opposed position model both to the left and to the right, and make sure the model fits in every combination before gluing it in.
This does mean that some models are very far back, rear hooves to the rear of the base, some are very far forward, normally in a gallop pose, at most the front hooves just clear the base, for most forward models the head does.
This way I can make a unit that fits in every combination and it looks dynamic as the horses are racing each other, not in a line. I don't try to exaggerate the line, there is visual coherency, but it is a charging horse unit not a parade line.
There is a sacrifice to be made here. My units bases this way are strictly
one rank only. This naturally fits ultra elite cavalry with multi attack model like Blood Knights and Chaos Knights.
And before you ask, Chaos Knights and Blood Knights are so long that multiple ranks would not fit even if I were to try and make a multiple rank unit. It would require a spacer. However that being said Having multiple single rank movement trays for said unit would probably work if you wanted to make a vampire of chaos cavalry deathstar.
OPTION 3.
If you have big models and want to have multiple rank cavalry then instead of alternating forward and back you alternate left or right. A good example of this working are boar boys. The old plastic boarboyz simply ranked up, but models were more contained then, especially cavalry. Prior to 7th there wasnt an issue of ranking up any cavalry that I remember, with exception to 5th edition cold one knights, but they were too expensive to rank up anyway.
Newer boar boyz fit on the bases, but are just a tad too long. You need to stagger then forwards and back a few millimetres to account for the feet of the riders touching, this is a standard problem with all cavalry and normally the base have enough leeway to accommodate this. Boar boyz don't because the tail sticks out and so does the snout. However adjusting the entire rank a few millimetres left or right will give enough clearance so the tail and snout dont touch. This means every rank is based a few millimetres astride from each other. It is not enough to look jarring.
Two considerations.
1. The character boar model is very big, it needs to be not mounted too far forward because it extends forward a lot anyway. Thankfully that models pig tail droops, and you will know that the snout of the pig behind will be orientated a little to the side opposite the ranking of the front rank. So you know where the snout will be. You can thus mount that model fairly far back and mostly central on the base. Now place that model on front corner of the unit opposed to the lean of the front rank. It will not be positionable in the unit easily and keep the boar boyz a multi rank unit.
Alternately pose the big pig on a rock and position it dead centre, this can now fit in the unit anywhere on the front rank. I tend to avoid mounting too many models on rocks, its cliche, but it is an easy escape with an awkward model. I recommend you do this here though as it will be he only way to have two boar riding characters in the unit.
2. The front corner model away from the lean, i.e the model naturally in the position where the character should go will look slightly odd. Ad the lean to left or right is covered by the unit every other model will look ok. Please note that the lean does not take the model over its base to left or right, but does take it to the edge of the base. Back rank end models also look ok. By the front rank corner model away from the lean will have a visible gap on the base he looks like he is avoiding. Place a piece of base scenery here, my preferred recommendation is a log, something low to the ground the pig might be porting around, big enough to occupy the space and yet low enough to to interfere with a character model if this model is shifted over.
If you try this method dryfit a lot so you can minimise the shift, you don't want a 'herringbone' pattern or anything weird, it only take a millimetre or two to create clearance, if done right the gap will only be obvious on the front opposed corner figure, and there will be room for additional shuffling forward or back and the occassional slight diagonal (no more than one pig in ten) to make the unit look natural.
I use big blocks of boar boyz for theme, and find this works even with the newer and far better boars.
