Is there a way to see if an object is in the same room as another object?

you use the built-in 'parent' Attribute, for an example:

(relevent part from a) default new game's code:

<object name="room">
  <object name="player">
  </object>
</object>

is the exact same as:

<object name="room">
</object>

<object name="player">
  <attr name="parent" type="object">room</attr>
</object>

---------

Quest's 'Object' Elements work exactly like the folders on your computer and/or an outline:

C:\\ Drive
-> Programs Folder
->-> Quest Folder
->->-> quest.exe File

HK
-> pants
->-> wallet
->->-> $1

Earth
-> North America
->-> United States
->->-> California
->->->-> San Francisco
-> Asia
->-> China
->->-> ??? (I don't know if China have states/provinces/territories? I don't know much about China, sighs)
->->->-> Beijing

Quest uses a html/xml (webpage languages) like code for its "actual physical stuff" of its game code, so that means you have start and end tags:

a "thing" block shown vertically:
(start tag)
-> contents
(end tag)

a "thing" block shown horizontally:
(start tag) contents (end tag)

<asl version="550"> // (start tag)
-> <include ref="English.aslx" /> // (start+end tags)
-> <include ref="Core.aslx" /> // (start+end tags)
-> <game name="blah"> // (start tag)
->-> // contents (start+end tags)
-> </game> // (end tag)
-> <object name="room"> // (start tag)
->-> <object name="player"> // (start tag)
->->-> // contents (start+end tags)
->-> </object> // (end tag)
-> </object> // (end tag)
</asl> // (end tag)

conceptually, what these would look like with having start and end tags (being tag "blocks"):

C:\\ Drive (start)
-> Programs Folder (start)
->-> Quest Folder (start)
->->-> quest.exe File (start+end)
->-> Quest Folder (end)
-> Programs Folder (end)
C:\\ Drive (end)

HK (start)
-> pants (start)
->-> wallet (start)
->->-> $1 (start+end)
->-> wallet (end)
-> pants (end)
HK (end)

Earth (start)
-> North America (start)
->-> United States (start)
->->-> California (start+end)
->-> United States (end)
-> North America (end)
Earth (end)

containment (Child-Parent) heirarchy:

grandfather
-> father
->-> son
->->-> grandson

grandfather is the main (root) parent
grandfather is the direct parent of father
grandfather in the indirect parent of son and grandson

father is the direct child of grandfather
father is the direct parent of son
father is the indirect parent of grandson

son is the indirect child of grandfather
son is the direct child of father
son is the direct parent of grandson

grandson is the direct child of son
grandson is the indirect child of grandfather and father

grandfather.parent = null
father.parent = grandfather
son.parent = father
grandson.parent = son

------------------------

what would the heirarchy look like if I did this?

grandfather.parent = null
father.parent = grandfather
son.parent = father
grandson.parent = grandfather

Answer:
grandfather
-> father
->-> son
-> grandson

and this?

grandfather.parent = null
father.parent = son
son.parent = grandfather
grandson.parent = father

Answer:
grandfather
-> son
->-> father
->->-> grandson

and this?

grandfather.parent = father
father.parent = son
son.parent = grandson
grandson.parent = null

Answer:
grandson
-> son
->-> father
->->-> grandfather

------------------------

anyways, back to your question... lol

// object_X.parent = room
// object_Y.parent = room

if (object_X.parent = object_Y.parent) {
  msg ("object_X and object_Y are both contained within the same object)
} else {
  msg ("object_X and object_Y are not both contained within the same object")
}

// output: object_X and object_Y are both contained within the same object (room)

VS

// object_X.parent = room
// object_Y.parent = room2

if (object_X.parent = object_Y.parent) {
  msg ("object_X and object_Y are both contained within the same object)
} else {
  msg ("object_X and object_Y are not both contained within the same object")
}

// output: object_X and object_Y are not both contained within the same object (room vs room2)

VS

// object_X.parent = room2
// object_Y.parent = room2

if (object_X.parent = object_Y.parent) {
  msg ("object_X and object_Y are both contained within the same object)
} else {
  msg ("object_X and object_Y are not both contained within the same object")
}

// output: object_X and object_Y are both contained within the same object (room2)

-------

besides the built-in 'parent' Object Attribute, there's also the:

'Got', 'Contains', 'ListContains', and/or 'DictionaryContains' Scripts/Functions too