geom_sf() legend doesn't show a label

Question

It's my first time making graphs with geom_sf (and ggplot2), so I'm facing some difficulties. I'm working with two datasets and I can't figurw out how to change the legend. I'm using ggmap and omsdata for the baseline.

`bl_basemap <- get_map(location = getbb("belluno"), zoom = 9, maptype = 'toner-hybrid', source = 'stamen')
ggmap(bl_basemap) + 
  geom_sf(data = geobelluno2cdp, aes(colour = f, size=f), inherit.aes = FALSE) + 
  geom_sf(data = geopnasc, fill = "red", color = "red", inherit.aes = FALSE) +
  guides(color = guide_legend(override.aes = list(fill = "red")))+
  coord_sf(crs = st_crs(4326)) +
  xlab("LONGITUDINE") +
  ylab("LATITUDINE") + 
  ggtitle("Belluno (2022)") +
  theme(plot.title = element_text(hjust = 0.5))`

This code prodices the following plot

I'm trying to add the red points to the label under the one already present.

I tried adding show.legend = "point", but the red points show inside the blue points.

`ggmap(bl_basemap) +
  geom_sf(data = geobelluno2cdp, aes(colour = f, size=f), inherit.aes = FALSE) + 
  geom_sf(data = geopnasc, fill = "red", color = "red", inherit.aes = FALSE, show.legend = "point") +
  guides(color = guide_legend(override.aes = list(fill = "red")))+
  coord_sf(crs = st_crs(4326)) +
  xlab("LONGITUDINE") +
  ylab("LATITUDINE") +  
  ggtitle("Belluno (2022)") +
  theme(plot.title = element_text(hjust = 0.5))`

How can I solve this problem?