understood. yes. you can do that.
since you did an all-shaman team, everyone's keybindings were identical. you press 1, everyone did lightning bolt, you press 2, everyone dropped totems. etc. etc. but for a mixed set, you do not really need to have every key bound to an action for every character, since each character will have its primary duties.

if you tank with the pally, i would suggest leaving the first attack, maybe avenger shield or consecrate on a seperate button, or at least, but it on a button that, for other slaves, require a modifier to perform the spell.

lets put it this way. for example, button 1, lets say you want to consecrate, but you dont want your shamans to dps... yet. what you can do is leave consecrate as a spell with condition [nomod]. like so: "/cast [nomod] Consecrate". it will cast consecrate for every time you press it but will NOT cast it if you press either ALT, SHIFT, or CTRL with it. great. what now?
on your shamans, the dps-ing shamans, you can place in button 1 this macro: "/cast [mod:alt] Lightning Bolt". you dont want your healers healing unless they have to, so i would leave those buttons empty at all times for the tank and the dps. with other attacks, you might want to sync their attacks together depending on what you want to do. i havent played my pally after the patch, but before i would not have my dps/heals do anything when changing seals. but they will do something when i hit a judgement.

you can also split the keys between the three groups. i would think of 1-5 as the pally's keys. 6-0 as the dps keys. and the last two keys will be for the healing. remember, macros will help greatly when condesing several spells into one key either by using modifiers or conditions. modifiers are ALT, SHIFT, and CTRL. you can double that up by making it even more specific LALT, RALT, LSHIFT, RSHIFT, LCTRL, RCTRL. and then there are conditions like harm, help, combat, etc. where if your target is harmful, kill, but if your target is not harful, cast a healing spell.

have fun with macros! they're awesome to use and makes your life a lot easier.