R Plotting three timeseries in two facet_grids in ggplot

Is it possible to plot three timeseries in only two grids using ggplot and facet_grid()?

# Create some fake data
stock1 = cumprod(1+c(0, rnorm(99, 0, .05)))
stock2 = cumprod(1+c(0, rnorm(99, 0, .075)))
indicator = sample(1:50, 100, replace = TRUE)
date_seq = seq.Date(as.Date("2023-01-01"), length.out = 100, by = 1)

df = data.frame(date = date_seq, stock1 = stock1, stock2 = stock2, indicator = indicator)

Now I would like to see an upper graph with the two stocks and one lower graph with the indicator using facet_grid().

The only result I get is a three-grid plot

grid_df = pivot_longer(df, c(stock1, stock2, indicator), names_to = "underlying", values_to = "values")

ggplot(grid_df, aes(x = date, y = values, colour = underlying)) +
     geom_line() +
     facet_grid(vars(underlying), scales = "free")

I dont know how to group the two stocks to bring them into one grid.

Thanks for help!

You could add an extra column to your longer format data where you could combine the stocks 1 and 2 to one string called stocks and leave the indicator alone using an ifelse to assign them to the facet_grid like this:

library(ggplot2)
library(dplyr)
library(tidyr)
grid_df = pivot_longer(df, c(stock1, stock2, indicator), names_to = "underlying", values_to = "values") %>%
  mutate(grids = ifelse(underlying == "indicator", "indicator", "stock"))

ggplot(grid_df, aes(x = date, y = values, colour = underlying)) +
  geom_line() +
  facet_grid(vars(grids), scales = "free")

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