Dota – shortcut to switch between sentry and observer ward when quickcasting

I asked a similar question, and you can find the answer for both setting multiple keys to one action and one key to multiple actions in there.

Set 2 buttons to same action

Lane support is also called a babysitter because the hero will basically babysit the ally carry to help him grow faster and without too much danger. Being a babysitter means:

1. observer wards close to the lane
2. harassing the enemy (best done with a ranged support like dazzle)
3. Denying creeps to disable some xp from the enemy
4. Not last-hitting any creeps and creating space for your carry to move around without any danger
5. Using the pulling techniques for keeping your own creeps next to your towers
6. Using the hero-attack technique (i do not know how it is really called), where you have to stay behind your wave of creeps and right click an enemy hero, so that the enemy creeps start attacking you, and they will move inwards to your lane, leaving them exposed for the carry to dispose of them more safely.
7. Providing occasional tp's/healing salves/sentry wards for heroes like Broodmother/Rikimaru/Phantom lancer/Bounty hunter,etc

The Support is usually assisting the whole team, and he's not focused on babysitting even though he might do something similar on the lane. Though the support role is encouraged to get some kind of farm to provide certain items (Mekansm, pipe, etc) that will be necessary to the team, where the babysitter or lane support, focuses on sacrificing a support's money and early game towards a fast rush to success from the main carry.