[knot-dns-users] Set propagation-delay based on multiples of SOA TTL, doable?

Hi, I wonder if it would be possible that one may use arithmetics in knot.conf such as: propagation-delay: 5 * dnskey-ttl I'd like to set a propagation-delay safety net during ZSK rotations depending on SOA TTL set for any given zone. As dnskey-ttl defaults to zone SOA TTL that would allow for propagation-delay definitions as multiples of SOA TTLs. As I couldn't find that in the documentation, I do assume that this cannot be done, right? Are there alternatives at hand I overlooked? Regards, Michael