Increasing your bloodline
Your can increase your Bloodline Score (BL) by expending RP. This is a Free Action. You must spend a number of RP equal to the score you are trying to reach. You can only increase the score by a single point at a time. You can increase your Bloodline Score no more than once per Domain Turn.
Example: You have a Bloodline Score of 25, and you have saved up 50 RP. Now you've decided you want to incrase your score up to 27. The first turn you pay 26RP, bringing your score to 26. On Turn 2, you spend another 27RP to raise it to 27.
Other ways to increasing your bloodline is to be invested with anothers bloodline. That can increase it with a few or many points depending on your relative bloodline strengths, you can increase it through bloodtheft, or some other strange things might happen that does it for you.
If you cross the "safe RP storage" border, there is a chance that you will automatically be drained RP to increase your bloodline.
Decreasing your bloodline
Sometimes you find that you need more RP and quick. One option is to sacrifice one point of Bloodline Score. Doing this is a Free Action. One point of bloodline score can be expended this way every month. For each point sacrificed you gain half the amount of your current bloodline (rounded down) in RP.
Example: You have a bloodline score of 36. You really need a lot of RP fast. So you decide to sacrifice a point of bloodline to gain RP. You now have a bloodline score of 35, but you gained another 18 RP to use on your turn.