You might consider adding the berries to secondary, you'll get more fresh fruit flavour that way. Adding the berries to primary is certainly fine, but the primary fermentation will alter the fruit's flavour. I've done both (with plums) to add depth to the end product with good results. Now I need to do a search for "rowan berries." Thanks for the tip on Ash berries being called rowan berries, I've never used them, but I'd like to. Regards, GF.