Merge uni- and multivariate regression in plot_summs / legend override issue

[bsim95]

Is your feature request related to a problem? Please describe.
I am currently trying to merge uni- and multivariate regression results from 6 "predictor" variables in the same forest plot using plot_summs, so I can visually summarize the individual regression of a parameter compared to a multivariate analysis.

While I know that I can set up 6 univariate functions and 1 multivariate function (with lm...) and plot them, this runs into issues when trying to set up a legend that summarizes all "univariate" into one legend item (next to the "multivariate" item). I tried several workarounds with scale_color_manual ( breaks (...)) that achieve a manual creation of a "univariate" and "multivariate" item, however, then there is still a default mode of variables (Model 1, Model 2, Model 3 ..., Model 7) that I cannot remove.

Describe the solution you'd like
Option 1 (preferred): Implement the Option to summarize a group of lm models into one group corresponding to one legend item
Option 2: Implement an option to manually decide on the legend items to be shown
Option 3: suggestion how I can fix the described problem when using the scale_color_manual function, that the default legend items (Model 1 ...) still shows up and cannot be removed

Describe any alternatives or other implementations that you might know of
See above.

Additional context
Example code on the problem, how I tried to fix it:

Load necessary libraries

library(jtools)
library(ggplot2)

Example of linear regression models

fit1 <- lm(mpg ~ wt + hp + qsec, data = mtcars)
fit2 <- lm(mpg ~ wt + hp, data = mtcars)

Create the plot_summs plot without the legend

p <- plot_summs(fit1, fit2,
model.names = c("fit1", "fit2"),
colors = c("blue", "red")) +
theme(legend.position = "none") # Remove default legend

Add the custom legend

p <- p + scale_color_manual(
name = "Models", # Name of the legend
breaks = c("fit1", "fit2"),
values = c("fit1" = "blue", "fit2" = "red"), # Adjust colors as needed
labels = c("f1", "f2") # Adjust labels as needed
) + guides(color = guide_legend(override.aes = list(linetype = c(1, 1), shape = c(16, 16))))

Position the custom legend

p <- p + theme(legend.position = "right")

print(p)