European Players: Your version of Harvest Moon DS does not have the GBA connection functionality. Putting in your EU copy of Friends of Mineral Town into the DS GBA slot will do nothing, as the feature was removed by Rising Star. You unfortunately will not receive extra music records or the FoMT village visitors.
cartriges To get the bonus content from Harvest Moon DS you will need to plug your copy of Friends Of Mineral Town or More Friends Of Mineral Town into the DS' Gameboy Advance slot. When you start your DS game it will activate the link between the two games. You don't have to do anything else.
The Japanese versions of the game can only connect to their own Japanese counterparts. The NTSC English version, on the other hand, has no problems connecting to the PAL version of Friends of Mineral Town even though the two games are from different regions.
Putting your GBA game into the DS' GBA slot does NOT allow you to visit Mineral Town from the DS game. There is no way to visit each games' towns unless you're playing that game; Mineral Town can only be visited if you are playing the GBA game, and Forget-Me-Not Valley can only be visited if you are playing the DS game. You cannot travel from one town to the other town.
Weekly Visitors
The main change that occurs is the weekly appearance of the bachelorettes and bachelors from the Mineral town games. The characters will start their designated weekday in the back hall rooms on the 2nd floor of the Inn, then walk to various locations in the valley. The special visitor Mary is the only exception. She will start out at Romana's mansion. Gotz will make weekly appearances, and Kai will visit every Summer even if you don't connect your GBA game to the DS.