LTspice stacks data points on the same vector when I do linear parameter sweep
LTspice is quite capable and the .MEAS card is very important and, for some things, the only way to achieve them. It's not completely clear to me what you seek, but I can set up a simplified schematic to illustrate what I imagine may be closely related to your question. So I'll take a guess and hopefully it will stimulate your ability to get an answer to your question.

I'll set up a simple 1:1 transformer, which will require that I use a mutual inductance card (.K). Although not shown on the schematic, I added a parasitic series resistance, to both primary and secondary, of \$50\:\text{m}\Omega\$. The rest is shown on the schematic below:



You can see both the schematic I used as well as the resulting current waveform in \$R_1\$.

The next step I take is to select the View\SPICE Error Log menu selection, which pops up a nice dialog showing the results of the measurements I made. (See the .MEAS card on the schematic for details.) Then I right-clicked on that dialog to get what you see here below:



The above shows the highlighted selection I want to make. So I selected that and received the following chart:



That's an approach to what I think you are asking about. But as I said I'm not entirely sure about that. But hopefully I managed to guess right.