function getNodesById(id){
    return collection.find({sid:id}).fetch();
}

Template.navigation.getNodesById= function(id){
    return getNodesById(id);
}

Template.body.getNodesById= function(id){
    return getNodesById(id);
}

<Template name="navigation">
...
{{#each getNodesById '1'}}
...
{{/each}}
...
</Template>
<Template name="body">
...
{{#each getNodesById '1'}}
...
{{/each}}
...
</Template>
...
<Template name="...">
 .....
</Template>

<Template name ="a">
   {{#each  functionA ...}}
   {{/each }}
</Template>

<Template name ="b">
   {{#each  functionA ...}}
   {{/each }}
</Template>
<Template name="...">
    {{ #..  functionA ...}}
        ....
     {{/...}}
</Template >

<Template name ="a">
   {{#each  functionA ...}}
   {{/each }}
</Template>

<Template name ="b">
   {{#each  functionA ...}}
   {{/each }}
</Template>
<Template name="...">
    {{ #..  functionA ...}}
        ....
     {{/...}}
</Template >

Handlebars.registerHelper('currentUserName', function () {
    var user = Meteor.user();
    if (_.isUndefined(user) || _.isNull(user)) {
        return new Handlebars.SafeString("<i class='icon-spin icon-spinner'></i> Login");
    }
    return user.emails[0].address;
});

Handlebars.registerHelper('getNodeById', function (id) {
    return collection.find({sid:id}).fetch();
});