For what purpose would you need to add the end of the sample at the beginning?

also,

maybe optional with cutting off the end and adding zero at the beginning of the sample

i have two channels, with the same instrument and settings
The sample i draw in to the sample editor and then i copy it to the sample of the other instrument with the same settings.
Then i shift the sample a bit to one side (mostly to the left).
So the instrument it self gets a bit, what shall i say? Fatter or wider, let us say it just sounds cooler.
To do so i found different ways.
I can open or copy the sample into a editor, loop the wave some times an then shift the original selection a bit and cut it out, then i can paste the shifted wave into mod plug.
A other way is to draw the sample two times very similar but shifted to one side (i think this is a very poor-men's solution).
It is also possible to copy the sample in the sample editor and paste it into the other sample from a shifted start position but this will cut the last part, but i can more or less draw the last part at the beginning.
So i can create my own fat sound synthesizers in mod plug.
The whole process would maybe be quicker if i could just somehow select the sample and drag it beyond its sample-width and all that sticks out of the sample-width will get added to its beginning.
Just a little bit shift to one side with a key combination and arrow keys or with the mouse or a box where i can enter some sample amount to shift to one side would be very handy.
May there is a other quick solution which i have not found?
May you think it is silly because the wave will not necessary start at the zero position and so it will maybe click or pop when the wave starts, but when i fade in the instrument with a kind of attack, i guess its not so important as long the start and end of the wave is at the same amplitude position and as long there is no click or pop in the wave it self.
I hope you get a picture of what i mean.

So all you want to do is delay one of the two samples, and that's already possible as I said by using "Insert Silence" (the star icon above the waveform editor).

Maybe i am stupid, sorry!
I draw a sample and i create a instrument for that sample
then i copy the instrument and all settings and envelopes with it.
The new instrument needs a sample, which i copy from the first instrument.
So now i have two identical waves in two identical instruments.
Now i press the golden star and add some samples at the begin of the second instrument, but then the wave in one sample is longer than the other and where i add the slices they will be zero amplitude.
I more thought kind like .:"'¨'":. will turn into .:"'¨'":. or '¨'":..:" and so on, just shifting.
So i could draw a sample starting at 0 amplitude and also ending there. so it will not click, just like a sine loop.
Then shift it to one side, so the end will be maybe at +50% amplitude and not 0, but to keep it as a sine loop it should add the rest after its sample length to the start so the loop will always restart where it ends at +50% amplitude or what ever it drops out of the sample when it gets shifted to one side.
The sample as such it self would not get more samples or less, longer or shorter, just the wave would get shifted to a side.
May i can explain it with a picture.
If you start two times the same wave editor and let them play the same endless sine, then you select one wave of this sine in one editor and loop this, so the endless sine playing and the looped sine part would still sound the same if you play them endless, but then when you move just the selection of the single sine wave loop to one side on its own endless wave, the two editors still play the same sound but one editor will be out of phase for the amount, as the selection got shifted to one side, but the wave length never changes there is nothing added or removed. Its more like adding the end to the start of the sample.
I did try now with this star-button but it just adds 0 amplitude to the begin or end and then i still have to redraw the end at the begin and additionally i have to delete the additional slice at the end.
Is not about kind of delay with two vocals, its more about shifting phase of sample-based synthesizers.
I think its maybe to complicated and maybe i also cant explain it clearly, or i just miss some thing, may i stick to my copy paste shift approach.
But thanks any way, you have already done a lot for this world! :D

I see what you mean.
This probably wouldn't be used by people too often. But in the situation you described, it would definitely be worth having.
You could shift the phase of sounds easily enough with an external audio editor, then import them back into MPT--your DAW will never have everything you need for every situation.