Using existing points to interpolate into a curve

Hi Everyone,
I’ve been a using Rhino for quite a while now but i’ve never used Grasshopper.
Now I have a small project that could be a good intro to Grasshopper and I want to take the leap.

I’m sure this has been solved somewhere, but I can’t quite trace it back, here is my issue :

I have created a series of points directly in Grasshopper (with different techniques such as coordinates, point on curve, etc…)

Now I would like to interpolate with a tangent at each end.
When I make a path to the Vertices input of the Interpolate (t) function, it only allows me to have one point, which is not enough.

I have tried the “flatten” option, but it doesn’t seem to allow me to connect to more point.

Do you know what would be causing this problem ? (i’m using Rhino5)
I’m sure there is a way to compute all the points into a table of some sort and have this my input for the interpolate (t) but I can’t work out how.

Thanks for your help

LMB+Shift+Drag = Create a new wire without erasing old wires

That’s simple, huh !
Thanks HS_Kim