Magical Enhancement Stacking

My broad question is, "Are magical enhancements additive?" That is, when more than one enhancement applies to a spell, do those enhancements add when calculating minimum skill? Or, does one use the highest value enhancement to set the minimum skill? In the interests of clarity, here are some specific examples.

Ex. 1
My mage casts a displace self spell to teleport some distance. The Teleport enhancement costs 5 MP, so this clearly requires a minimum displacement skill of 5.

Ex. 2
Now, she casts a version of that spell that allows her to teleport (5 MP) at will (9 MP) over a duration. Does this require a minimum skill of 9, or a minimum skill of 14?

Ex. 3
Finally, she casts a version of the spell that allows her to teleport (5 MP) at will (9 MP) and skip forward 1 round in time (4 MP) every time she does so. Does this version demand a minimum skill of 9, 14, or 18?

And, last but not least, if the answers to examples 2 and 3 are both 14, how can one tell when enhancements add, and when they do not? Is it just the "for an extra 9 MP on top of your Teleport effect" language, or is there some more general rule of thumb at work?

Oh, and two bonus questions! (Lucky you.)
Would it be possible to make the the time skip portion of example 3 optional for each teleport? If so, what would that entail?

P.S. I was pretty frustrated with the magic system at first. Now that I've played a mage through to grade 16, though, I really like the way it fits together. The character's very fun, and has been surprisingly well balanced with the other characters throughout the game. My mage brings a pile of goodness to the table, but doesn't eclipse the three melee combatants (star knight, CHI-fueled martial artist, and mutant) at all.

Each enhancement has it's own prerequisite. You don't add the prerequisites together, you just have to meet the prerequisites of any enhancement you use.

But...yikes! You've played all the way to grade 16 wondering that? Why didn't you ask, like, 11 grades ago?

I didn't ask mostly because it didn't seem necessary until now. I'm finally moving into multiple signature spell territory, and am giving serious thought to how best to make combinations that fit my character's themes. For example, the med-evac spell, which teleports someone out of harm's way while it simultaneously heals them. And, with thought, I began to wonder about things like that.

Which brings me back to my bonus questions.
Would it be possible to make the the time skip portion of example 3 optional for each teleport? If so, what would that entail?

I'm asking because I have in mind a handful of spells with bennies like the optional time skip, but I'm not sure they're kosher in OLD's system.

Morrus said:

Each enhancement has it's own prerequisite. You don't add the prerequisites together, you just have to meet the prerequisites of any enhancement you use.

But...yikes! You've played all the way to grade 16 wondering that? Why didn't you ask, like, 11 grades ago?

Click to expand...

Probably because I would have been the one he asked and well... letting the question lie for a bit was just easier : )

I would probably have just come to the boards and asked too. I'm never right about these things. He asked me after he posted and at first I said he would need to meet the full cost with his skill, then we talked about it and I realized I was probably wrong. Like I've said in the past my gaming group is really good about putting up with my idiosyncrasies, which also means knowing when to blow past me with a question and get the answer from someone who they can be more sure of !

Thanks Morrus!