Copy a subsite from one site collection to another using site templete, will copy all the site collection columns to be defined as a subsite columns

Question

I am working on SharePoint server 2013 web application and i have a site collection of type team site named "business functions", and it have three subsites. where all the columns were defined inside the site collection level.

now i want to copy these 3 subsites to a new site collection (and i want to keep the original subsites as is ), so i did the following steps:-

1. i save the three subsites as site template.
2. then i download the generated wsp files.
3. i upload the three wsp site templates inside the new site collection.
4. after that inside the new site collection i created three new sub sites based on the 3 wsp site templates.

now from my first test i thought that the sub-sites were copied successfully. but after some detailed testing i realized that i am facing this strange problem . now on the original site collection i created all the site columns at the site collection level. for example here are 6 site columns defined at the site collection level (site collection name is Business functions):-

but when i create a new sub-site on the new site collection based on the site template, i have noted that these site collection columns will be created as a sub sites columns as follow (sub site named is dev):-

so can anyone adivce what is causing this problem and how i can fix this ?

second question. is there a better way to copy my sub-sites to the new site collection, and to keep the exact behavioure for the site columns and content types. ?

EDIT:-

here is how my content database looks like:-

Answer 1

If you don't have many sites, you can try copying the whole site collection. Since you wrote "copy webs to a new site collection", this approach would work. Make a backup of the site collection that has your web sites in it and restore it to a new site collection:

Backup-SPSite http://server_name/sites/site_name -Path C:\Backup\site_name.bak
Restore-SPSite http://server_name/sites/new_site_name -Path C:\Backup\site_name.bak

Then get all the webs except the ones that you want to leave (based on server relative url. Don't forget to include root web!) and remove them.

$webURLsToKeep = "/sites/new_site_name", "/sites/new_site_name/1", "/sites/new_site_name/2", "/sites/new_site_name/3"
$site = get-spsite http://server_name/sites/new_site_name
$site.AllWebs | ? {$webURLsToKeep -notcontains $_.ServerRelativeUrl} | ForEach-Object {$_.Delete()}

That way you would keep your site collection configuration including all site columns.

Hope this helps.

Answer 2

issue is you created the column at site collection, now you moving only the sub-sites but your columns are site level.

backup and restore is the best option. But within same web app you cant restore two site collections with same id in same content db. you need to create a new content Db then restore the site with new url.

another method i am thinking, you may try it. create the same column on destination site collection and then try import/export.