How i can change just one value on my object and keep my default value for the other values?

Question

i wanna do an update function , all my data is dynamic and sometimes i would like update just one value.

I set up my values , then i used the props default values to keep my value inside my input but when i wanna change just one input , my object update only the value i changed on my onChangeText.

How i can say if i don't write a new value keep my default value inside my object value ?

{CRMData.columns.map((element, key) => {
              return (
                <View key={key}>
                  {element.Header === "Update" ? null : (
                    <View>
// i set up the names of my differents input
                      <Text>{element.Header}</Text>

// i keep my default value thanks to the props default value
                      <TextInput
                        defaultValue={
                          modalBusiness
                            ? CRMData.rows[indexDeal][element.Header]
                            : ""
                        }

// i change my text by my current text 
                        onChangeText={(text) => {
                          console.log("text", text);
                          setValues((prevState) => ({
                            ...prevState,
                            [element.Header]: text,
                          }));
                          console.log("value", values);
                        }}
                        style={styles.input}
                        placeholderTextColor="#E8E2E2"
                        placeholder="prenom"
                      />
                    </View>
                  )}