Can I use WP to create a multisite importing the posts of 3 old WP website?

Question

I am pretty new in WP and I have the following doubts about work that I have to do.

I have to create a multisite (3 sites related together) starting from 3 separated old WP websites.

I know that some years ago there was WordPress MU that performed this task but reading the online documentation it seems to me that now WordPress MU is a closed project and that the multisite functions is natively implemented by the standard WordPress version, is it true?

So, if the previous assertion is true, can I do the following?

1. Use WP to create a multisite that implement 3 different sites (each one with a unique theme, widgets and configuration)

2. Take the posts of the previous old WP website and import it in the related new single site of my new multisite.

Can I do this things?

Answer 1

Yes, you can import content from other single site installations into one multisite installation (network). Widgets, themes and plugins are set per site in a network. What you cannot do is using multiple versions of the same theme or plugin, eg. version 1.2 on one site and 1.3 on another.

Before you do that, set up a local test installation. See Multisite on Windows with wildcard subdomains or WordPress in a nutshell: WT-NMP for examples.

Answer 2

Yes, you can. Just enable network in WP that can be easily done by define it in wp-config.php and then use domain mapping to set each of the 3 sites to a new domain. Importing old site posts easy task. For each of the sites new tables will be generated into database.