BERLIN—Opel will not split off its German factories from its operations, and production at the Eisenach plant will resume in January, Opel owner Stellantis and union IG Metall said on Wednesday, soothing fears over the marque’s future. Stellantis also said that the Grandland SUV, which was temporarily produced in France when Eisenach was shut down in September due to a global chip shortage, will be made exclusively in the German factory from the new year. German unions and politicians in the states have criticised Stellantis’ communication on its plans for the two factories, in Russelsheim and Eisenach. They said it had not been made clear whether the plants would be legally split off from Opel and if Grandland production would return to Eisenach. Stellantis had said in September that a split-off structure could be more efficient and flexible after German newspaper Handelsblatt reported this was under consideration. IG Metall said …