Can I create a variable to separate specific participants matched with Match-it based on the treatment group

I have a data frame as below where I have participant ID’s, 2 types of clinical diagnoses marked as 1 and 2, with control participants marked with 0.

I also have a subclass column that is the result of using the package Match-it – this has an output where each treatment variable with a clinical diagnosis has been assigned a control participant based on nearest neighbor matching.

df <- data.frame( ID = c(1,2,3,4,5,6,7,8),
                  clinical diagnosis = c(1,1,2,2,0,0,0,0), 
                  subclass = c(1,2,3,4,1,2,3,4))

summary(df)

ID Clinical_Diagnosis Subclass
1  1                  1
2  1                  2
3  2                  3
4  2                  4
5  0                  1
6  0                  2
7  0                  3
8  0                  4

I would like to create a simple variable where all participants with a clinical diagnosis == 1 and their respective matched control participants, in this case ID = 5 & 7 are assigned a value of 1 in a variable called match_group, and all participants with a clinical diagnosis == 2 and their respective matched control participants are assigned a value of 2.

I have tried to create two separate matching files and simply creating a variable based on whichever matching group participants were assigned from. However, when using full and exact matching processes with a larger dataset, I end up with duplicated participants which I can identify, however I want to avoid this and hence want to be able to derive this from a singular Match-it process.