How to say in a tandem in different languages

You can say in a tandem as tillsammans, parallellt in the following countries: Aland Islands; Sweden;

You can say in a tandem as sammen in the following countries: Denmark;

You can say in a tandem as tandem in the following countries: Estonia;

You can say in a tandem as tandēma in the following countries: Latvia;

You can say in a tandem as kartu in the following countries: Lithuania;

You can say in a tandem as в тандеме in the following countries: Russia;