[PvK]

Surrender should require acceptance from the recipient, and is worth considering to disallow it at all when setting up games.

However, in the case described, where two empires who were both partners use surrender to become one, it's not necessarily an advantage, depending on the circumstances. I already wrote about this earlier today, but a few points:

1. The union empire will be more likely to trigger and stay in MEE status.

2. The union can now only do 12 intel projects instead of 24.

3. The union can't trade with itself anymore, reducing production, research, and intel by up to 20%.

4. The union can only send one diplomatic message to each other empire per turn, instead of two. It also has to have one treaty state with each other empire, instead of being able to have multiple treaty states, which can be taken advantage of in several ways.

5. The union now has half the limit on max ships and units in space for the scenario, compared to what it had as two empires.

PvK