Clarification on hairpins with and without dynamic markings

Still somewhat confused about hairpins. I fully understand that hairpins require leading and trailing dynamic markings somewhere in the score and that only the first of a series of hairpins between a pair of markings will playback. I also understand that if there are no markings, the velocity change property of the hairpin needs specification (default is 0) for the playback to vary the velocity. My question is are these systems mutually exclusive? If so, then if I choose to use velocity change properties I cannot have dynamic markings and visa versa. How can I include dynamic property markings for printing the score that are ignored by hairpins on playback relying on using only velocity change properties. If they are not exclusive systems of implementation, if I have a hairpin that uses a velocity change property and another that does not and follows the first, is this then ignored even though it is the first hairpin with a zero velocity change. If this is not ignored, does the hairpin want to go back to the previous marking even though the current velocity has already been altered by the hairpin setting the change via non-zero property value.