I had reason to have a look at the evangelical alliance website and was interested to read some of what was said there. Nothing too unexpected in the statement of faith (11 points) but I was interested in the "Evangelical Relationships Commitment" that has 3 affirmations and 5 actions.
The affirmations are:
We welcome as Christian brothers and sisters all who experience the grace of new birth, bringing them to that fear and knowledge of God which is expressed in a life of obedience to His word.
We recognise our Christian duty of trust and mutual encouragement to all who serve Christ as Lord, not least to those who conscientiously prefer not to be identified with the same churches, alliances or councils as ourselves.
We respect the diversity of culture, experience and doctrinal understanding that God grants to His people, and acknowledge that some differences over issues not essential to salvation may well remain until the end of time.
I thought number 2 was particularly apposite to the situation with SMC. I don't know about others, but I have never seen them encourage anyone who was conscientiously preferring not to be identified with the same church.