SQL join multiple values on same column row

Question

My problem is as follows.

I have a database with certain Healthcare services. These services can have 1 or more emails that are stored in HealthcareServiceEmail with a foreign key referencing HealthcareService. I would like to show these emails in the Healthcareservice TABLE.

For this I would need to insert the values from HealthcareserviceEmail INTO the table Healthcareservice where their foreign key matches the key from Healthcareservice.

Because there can be multiple emails I would need to insert multiple values in the same cell. I would also need to insert them into already existing rows from healthcareservice (If I understand correctly). What I have for now is this:

CREATE TABLE IF NOT EXISTS ADMINISTRATION.HealthcareServiceEmail (
id BIGINT NOT NULL,
email VARCHAR(255),
healthcareService_id BIGINT,
name VARCHAR(255),
uuid VARCHAR(255),
PRIMARY KEY (id)
);

ALTER TABLE ADMINISTRATION.HealthcareServiceEmail
ADD FOREIGN KEY (healthcareService_id)
REFERENCES ADMINISTRATION.HealthcareService (id) DEFERRABLE;

ALTER TABLE ADMINISTRATION.HealthcareService
ADD COLUMN IF NOT EXISTS email VARCHAR(255);

INSERT INTO ADMINISTRATION.HealthcareService (id,email)
SELECT HealthcareServiceEmail.healthcareService_id,HealthcareServiceEmail.email from ADMINISTRATION.HealthcareServiceEmail
INNER JOIN ADMINISTRATION.HealthcareService ON ADMINISTRATION.HealthcareServiceEmail.healthcareService_id = ADMINISTRATION.HealthcareService.id

Now this obviously does not work, but I am not fully sure what to do to solve this as I have looked into SQL but it is definitely not my strong suit.

Right now I am trying to enter the Emails to show up at the right Service. I tried joining on the ID and inserting that into the email field for HealthcareService but my table does not fill up.