Making two data points in one variable one color while the rest are another color

Question

I have a dataset of acoustic receiver locations and want to highlight two of them on the map I am making. I would like two of them to be red, while all others are black. Here's my code:

geom_point(aes(x = receivers$long, y = receivers$Lat, color = receivers$Mooring), 
           data = receivers)+
scale_color_manual(values = c("TRF1" = "red", "TRF3" = "red"))

The error I get is:

Error: Insufficient values in manual scale. 36 needed but only 2 provided.

Is there any easy way to say "these two red, all others black" in R or will I have to create a separate vector specifying all the values?

Thank you!