here the solution
<script>
function add_months(datestr, months) {
var new_d = new Date(datestr);
new_d.setMonth(new_d.getMonth() + months);
return new_d;
}
$(document).ready(function() {
$('#fur').pickadate({
selectMonths: true,
selectYears: 10,
format: 'yyyy-mm-dd',
onClose: function() {
var date_add_m = add_months($('#fur').val(), 7);
$('#fpp').pickadate({
selectMonths: true,
selectYears: 10,
format: 'yyyy-mm-dd',
disable: [{
from: new Date($('#fur').val()),
to: date_add_m
}]
})
}
});
});
</script>
the input
<input type="text" name="fur" id="fur"/>
<input type="text" name="fpp" id="fpp">