Introducing a new Duck hen

First I would like to say thanks to this site. Super information that has helped me so much. I am new to having ducks, and was given a drake & hen that were hatched together and are now about 9m, I'm guessing. They were hatched in a school, and are VERY humanized. I was told they were Black Swede/Ancona crosses. She started laying about 1.5 months ago. He has become more aggressive to her, ie: not letting her in pond, pulling out neck feathers, etc. Lots of info I have read says 1 hen is not enough for the male. So I found a new hen, she is approx 1-1.5 yr. She is a Black Swede, and has been raised in a large flock of lots of birds. She is noticably bigger than the other 2. I understood the "pecking order" fights would happen. I didn't realize ducks hold a grudge, much longer than chickens. The original 2 will not allow her anywhere near them, yet she does try to creep into the group. The drake chases her constantly. Now I'm not sure what to do. Should I separate her? They have been together for 4 days with not much improvement. in a 30x33 sq ft run with "outtime" 2-3x a day in the rest of the property about 2/3 of acre total. The first 2 wont leave sight of her when they come out and she will follow them out but runs right back it.
Any suggestions are very appreciated.

 

Unfortunately no I didn't start with an intro period. My first hen (Lacey) talked her into coming out of the crate when we brought the new one (Betty) home. At very first the hens got along. Then Betty turned & chased Lacey. Now the drake beats on Betty. They have been locked up in the same house at night for the last 3 nights. Last night I panicked, (over protective pet owner), went running into the house & the 2 hens were sleeping face to face with the drake standing guard. This morning I let them out and he starts running Betty down.