How to modify a single attribute from multiple list of attributes

[Tom Leach]

How do I modify/delete a single attribute from the directory when I have 
multiple attributes of the same name.
For example, given the following ldif:
        dn: cn=config,o=dhcp
        cn: config
        objectClass: top
        objectClass: dhcpService
        objectClass: dhcpOptions
        dhcpPrimaryDN: cn=server1,o=dhcp
        dhcpStatements: default-lease-time 600
        dhcpStatements: max-lease-time 1200
        dhcpStatements: ddns-update-style none
        dhcpStatements: boot-unknown-clients on
        dhcpStatements: log-facility local7
How would I modify just one of the dhcpStatements: attributes, for 
example, change 'dhcpStatements: log-facility local7' to 
'dhcpStatements: log-facility local3'?

I've tried an ldif with:
        dn: cn=config,o=dhcp
        changetype: modify
        replace: dhcpStatements log-facility local7
        dhcpStatements: log-facility local3
But that just gave me an error:
        ldapmodify: Undefined attribute type (17)  additional info:
        dhcpStatements log-facility local7: AttributeDescription
        contains inappropriate characters.

I've also tried:
        dn: cn=config,o=dhcp
        changetype: modify
        replace: dhcpStatements
        dhcpStatements: log-facility local3
But that just gave me an error:
    replace modify:
        dhcpStatements
    replace dhcpStatements:
        log-facility local3
    modifying entry "cn=config,o=dhcp"
    modify complete
    ldapmodify: Undefined attribute type (17)
        additional info: modify: attribute type undefined

I can use 'delete: dhcpStatements' but that deletes all of the 
dhcpStatements and then I have to add all of them back with the 
modification to the one that's needed.

So, what ldapmodify/ldif syntax is needed to specify which of multiple 
attributes should be modified?
Thanks!
Tom Leach