"Next to" limitations

Many enhancement cards are required to be played next to other cards.  Chronoranger's Bounties, or Captain Cosmic's Constructs, for example.  Are there limitations on how many cards may be played next to another card, and if so what is that limit?  For example:

During his Play Phase, Captain Cosmic plays Cosmic Weapon from his hand.  He places it to the right of Legacy's character card.  During Captain Cosmic's Power Phase he reveals Autonomous Blade; now that Legacy has a way to deal damage he wants to place Autonomous Blade on Legacy.  Can the card be placed to the right of Legacy (currently occupied by Cosmic Weapon)?  If not, can it be placed to the left of Legacy?

As far as I know, there isn't any limit to the number of cards which can be in any of these positions.

Thanks!

The only limits are the ones stated on the cards themselves e.g. Expat's Guns say they may only have 1 ammo card next to them each (baring Pride & Predjudice).